# Utterly Stumped, Lights dim after big 3, new 200 amp alt and a Cap.



## orion0469 (Oct 18, 2017)

2005 Chevy Silverado 4.3L 2 pin AD244 custom built 200 amp alt HD rectifier bridge from alternatorpartsDotcom Installed a Kenwood XR900-5 amp 60x4 + 400x1 watt RMS 1 farad Cap Big 3 plus 1 done with 0 gage awg running 4 awg to amp and cap oxy free fine strand. Autozone duralast gold 1000cca brand new. brass side term. no load 14.5 volts. max load 14.5 -14.9 volts. Cannot get this Damn thing to stop dimming the lights everytime the Bass hits. and it is only dropping Voltage less than 1 volt . Cap is reading constant 14.7 . Nobody on earth is able to answer this. I am at my wits end. Does anyone know Anything about this? I am fully aware of GM's RVC and how the 2 pin systems work. This should not even be effecting this in Any way. This is assuming I am getting this result at full power with gains all the way up which is not the case. amp gains not even half way up. Volume on my Kenwood BT958HDC is at 18 when this occurs. Voltage across Amp is steady 14.4 no drop what so ever. Cap shows less than 1 volt when this happens. key off Does not occur. no load voltage maintains 13.9-14.7 light on mode seems to help but still happens. and mind you I am listening to Rock, But good example is "Better man" Rag-n-Bone Man. every note below 100MHZ. I am Desperate at this point. I have completely used every trick I have ever learned. Is it possible that the Lights are getting a signal or voltage draw from another source? the Head unit's internal amp is disabled but it would still draw voltage to signal the preamp outputs. II have tested voltages at the back of head unit and they are steady 12v. Any information ..and I mean Any is greatly appreciated. btw I am not willing to add a second Alt or Battery. this is not a competition set up. it is a low end upgrade to a stock stereo. I just dont get it.


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## stevemk07 (Jan 3, 2012)

Did you try taking the cap out of the equation?


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## orion0469 (Oct 18, 2017)

Cap was a last resort. It occurs at every point. just amp. then I added the Big 3 no change. Then I replaced the Alt. no change. I grounded head unit off the chassis harness. shortened power lead to amp 3 feet. and ground, replaced Amp. Rerouted everything. RCA's middle under pass seat. power lead driver side, 9 strand speaker with durashield in the plastic conduit driver side. no change.


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## gijoe (Mar 25, 2008)

Wow, with that amp you don't need a cap, high output alternator, or big 3. That amp will run off of a moped. Maybe take all of the unnecessary junk out of the equation, starting with the cap.


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## orion0469 (Oct 18, 2017)

done and done. same issue. back to square 1. this set up should run at least a 2k RMS system. Im "as the title says "utterly Baffled"

I am tempted to remove the head-unit off of the factory harness remove the door-chime box and see if this may be the issue. I could not see how or why though. best I can come up with is it is somehow seeing signal from the BCM to the ECM and the radio circuit through the Dimmer switch. but volume impacts it. so it Must be outside of that. or it would be constant throughout all volume ranges and occur with ignition off.
but it doesn't.
Key on engine off does not do it.
so it is only Isolated to the charging circuit. 
which leads me to the RVC system which is not bypass able nor configurable on a 2pin alternator system. And I am sure there has to be someone in this world that has installed an aftermarket system on a full size GM truck since 2005 that has had same issue and found solution or workaround but alas this is going on 6 months of me searching and searching everyplace. mechman makes a 4 pin module to override the RVC and tune the voltage but only for a 4pin system.


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## orion0469 (Oct 18, 2017)

If the RVC is the issue though some car audiophile has to have come up with a fix. some way of faking the BCM into going into chargemode and staying there.
the only non-fault mode that seems to help is lights on mode which only increases the min voltage the battery sensor triggers charging mode. which changes from 13.5 to 13.9 or 14.4. it fluctuates. its the same problem many guys have with the voltmeter in the dash bouncing. big 3 stopped that. when the bass hits the voltage doesn't drop across the cap more than 1 volt. across the battery its almost negligible. across the amp it is steady 14.4 which is its rated voltage. Tried using an old school bazooka mono amp i use to have in this same truck and it never occurred and its a 500 rms mono amp. and it does it now. toned all speaker leads. no loops. amp would error out if it was a bad speaker ground issue. so would head unit. verified that through crutchfield and kenwood both. they even replaced the amp for me for free. I loaded this thing up threw an ammeter on it and im not even pulling 90 amps, voltage stayed constant under both load and no load conditions. 14.7. the 90 amps is with the electric fans on too.


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## RockamyZ (Apr 29, 2017)

Try a different battery. New isn't always better.


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## bnae38 (Oct 3, 2015)

Have you tried a dedicated ground run?


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## Theslaking (Oct 8, 2013)

Just trace the voltage drop back. I've done it before and found a broken wire. Gijoe is right. Your truck should run all that without problem. I have had 1000+ worth of potential amp power rocking in my 05 Silverado with no real electrical issues. It's not the electrical systems design. The factory alt is 160 amps to begin with. Something is broken. If it's only the headlights switch to led. They take way less power.


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## Theslaking (Oct 8, 2013)

Let me add that I also run a plow with that truck. There's no better time to blast music than when you're riding around plowing.


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## Locomotive Tech (May 23, 2016)

Looked at the Duralast battery on Autozone's site, it doesn't say that it is an AGM. If it were me I would switch to beefier AGM design. 

Are you still running Halogen head Lamps?

Is the dimming so bad that it is unsafe?

Are your headlight covers oxidized?

Have you considered putting caps in the headlight circuit?

At 13 years old the dimming could be inherent due to the oxidation on connections/terminals over the years, cleaning these will not hurt.

Have you seen dimming with the audio off and engaging the A/C, defroster, brake pedal at the same time? Do this at night.


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## Theslaking (Oct 8, 2013)

Duralast gold isn't AGM. The Platinum is. But really I have this truck with more potential power draw and have no issues. In my 2000 Silverado, which have had way more powerful systems all I did was take an 190 amp alt out of a Cadillac and nothing else. Actually have an duralast gold in it. It's only an 880 cca I believe. You need to consider the types of issues that Locomotive Tech suggested.


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## Locomotive Tech (May 23, 2016)

Uh, Ok, what was wrong with those questions?


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## Theslaking (Oct 8, 2013)

Nothing. I edited my last sentence.


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## Locomotive Tech (May 23, 2016)

Theslaking said:


> Nothing. I edited my last sentence.


Ok Whew! been into the beer tonight and had to read my questions several times. Thought the OP was a lady for few minutes too.

OP, I know it may be rather annoying, but like everyone seems to agree you have enough power, my questions are the easy ones. I would say you have a weak ground somewhere. Following the voltage drop is not an easy task but you will be better for it.


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## lurch (Jan 20, 2014)

Good points, i was going to suggest looking at the headlight grounds and
Associated circuits. 
The vehicle is old enough now that it warrants investigation.


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## Holmz (Jul 12, 2017)

Theslaking said:


> Just trace the voltage drop back. I've done it before and found a broken wire. Gijoe is right. Your truck should run all that without problem. I have had 1000+ worth of potential amp power rocking in my 05 Silverado with no real electrical issues. It's not the electrical systems design. The factory alt is 160 amps to begin with. Something is broken. If it's only the headlights switch to led. They take way less power.


If the amp is connected to the battery, and the lights dim, it would seem like the current is flowing...

Depending on the control circuit of the alternator, it is possible that the the alternator is not keeping up to the pulsating draw... Is it better or worse with the capacitor?


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## LBaudio (Jan 9, 2009)

should be bad/unclean connection somewhere in the electrical system


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## orion0469 (Oct 18, 2017)

Thank you all for your Response to this. I will do my best to address each one of your responses. 

1. Issue occurs (Entire lighting circuit. not just headlights.) Dash illumination, interior light, bed light, running lights only when the Engine is running and the ignition circuit is isolated. meaning the truck is not using battery to provide power to operate. I can remove the fusable link and the issue still exists. Dimming only occurs when volume on radio is turned up and the Bass from the music hits. AC, Wipers, Highbeams, nothing else causes this. 

2. I am running stock original headlamps. no joke. only have 112k miles on this truck. 90k of it all highway miles. I will check for Oxidation on the Terminals. Still unlikley because I am anal and use silicon paste on everything. Ground for headlamps wire wheeled and siliconed. I went through this like the hand of god. every ground, cleaned and protected. 

3. I have thought of an agm battery. The battery could never cause this issue. I see that suggestion all over the place. in theory. you could remove the battery and run entirely on the charging circuit. the Fact this ONLY occurs when the engine is running eliminates that as being the issue.

4. What do you mean a dedicated ground? Like something you would run for a unibody vehicle that does not have an actual frame? I have noticed Alt whine that does not increase with RPM and also noise from blower motor and wipers.
I grounded the head unit to the Dash mounts to truck cab under the dash. and it got rid of 90% of it.

5. Voltage drops. Where would I even begin? I dont have a location that I could turn volume up loud enough for an extended period of time...neighbors and all being not 15 feet away. Any recommendations on best process? use maybe a test tone? I am not getting any drops across the battery. or the amp. Ive checked all the Relays and they operate normally. 

At this point I am troubleshooting. My thought on this whole thing is exactly what Gijoe said. This should not need any of the things I have invested time a nd money on. I went down the RVC rabbit hole and thanks to your input I believe it cannot be that. (or Shouldnt) I have no true way of testing that. I could buy a 3k fluke obd programming unit and try to reprogram the Prom on the ECM but that would probably catastrophic. I have been out of the Automotive tech field for 20 years and am not up to par on alot of the newer electrical systems on these vehicles but I am very well versed in the foundations. My experience tells me this is a ground issue. Even if this is a ground issue the electrical system Should compensate. what is troublesome is the fact the Cap did absolutly nothing. 
so this is occuring outside (before) that circuit.
could this be a grounding issue under the dash someplace?
For the headunit
would you recommend running power straight to the battery and to the switched side of the fuse block? run a ground straight to the battery?
I wouldnt think this would be for a permanant solution but for testing to help isolate?
I have a feeling that the Alternator circuit is grounding someplace. the Fact I pull the fuseable link off and there is no change. Usually you will hear an audible change in the alternator. and without an OBDII scanner with BCM access I cant watch output changes. there is no True L terminal on these. an F and a L but the L is a signaling output to the BCM not like prior RVC systems. F is the Field Terminal if im not mistaken. Im use to 1 wire...lol normally I would put a dmm on that and pull the link to watch it drop.

All input is Greatly appreciated. Thank you in advance
PS : I cannot thank you all enough. I have posted to more than 10 forums in the past 6 months and this is the only one who has had Any response.


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## Holmz (Jul 12, 2017)

Your reasoning seems good to me.

1) if the lights dim, then I cannot envision a broke wire issue. The only way for the lights to dim is that a massive amount of current is pulling down the system. This requires good connections between the amp circuit and the headlight circuit.
It is possible that the alternator or battery connections could be bad, but the amp and headlights are great if the amp is pulling the headlights down.

2) with the battery disconnected then if the lights flicker with the base notes it means that the alternator is Not keeping up.
One way would be to play subwoofer tones out of the amp. You can turn up and down the volume to see if the lights dim.
If the lights only dim initially when the sound is cranked, and then they come back up to brightness, that would indicate that the alternator's control circuit is damped so as to not respond to a quick transient current draw.

3) The battery is a capacitor.
I would suspect that a "deep draw" type of design would have less "fast capacitance" then a liOn type of battery.
A battery designed to have a high amount of CCA would seem to be able to fill in the alternator voids.(???).

I would assume that the capacitor would have helped?
What size was/is the capacitor?


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## jaandrade79 (May 17, 2017)

That does seem like overkill on that amp and setup.

I used to use a cap when I was running a 1000 watt mono block and a fosgate 360x4 back in the day but my 500x1 alpine and 45x4 mini alpine amp run fine off my 4awg power wire in my 2014 Silverado. No dimming when my jl12” hits. When I use my power window it dims more than when the amps do. 

I wish I had something to help you out but I don’t know what the deal could be. I would think there is a lot of headroom in that system and the headlights would not dim. You didn’t run a long ground wire did you? Good luck brother


Sent from my iPhone using Tapatalk


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## Theslaking (Oct 8, 2013)

Regular caps are a waste of money. Forget you ever bought it. Some add additional grounds to the alternator for ridiculous draws. Only the two parts ground where it bolts to the block. So adding more ground surface can help in high power situations. Not likely here. 

Start searching for the voltage drop right at the headlight. Then see if it drops at the next junction point (fuse, split, relay, regulator,etc.). Keep going back until you find a broken something or no voltage drop. Could take a while. 

The battery is super important for car stereo applications. The alternator won't likely keep up to heavy and extended music. That's normal. That's why there is a battery. It should however be able to recharge the battery before you notice a problem. So removing the battery won't do anything but prove the alt can't do what it's not designed to.


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## brewmastr (Jul 3, 2015)

Have you used an amp clamp to capture what your amp draw is normal vs when bass hits. I think you have gone very far beyond the basics here without covering the basics first. if you have more amperage demand then can be handled by the alternator it is going to cause the voltage to dip and lights to dim. Once you know what your amperage situation is we can start determining if your amp has excessive internal resistance acting as a load or if your alternator is just not charging up to par. If you had bad ground paths in the headlights and such this wouldnt just be a problem when the bass hits. There is a underlying cause here and knowing your amp draw on the vehicle will greatly assist.


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## Holmz (Jul 12, 2017)

The new cheesehead (fellow) @MWisBest has something which may pertain.

http://www.diymobileaudio.com/forum...369106-new-take-fixing-headlight-dimming.html

Stories about cables, etc, do not replace what a knowledgable person using an oscilloscope can do.

It may be a difficult problem to overcome given how an alternator works.


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## Theslaking (Oct 8, 2013)

Holmz said:


> The new cheesehead (fellow) @MWisBest has something which may pertain.
> 
> http://www.diymobileaudio.com/forum...369106-new-take-fixing-headlight-dimming.html
> .


You're right! Changing the blinker fluid is a great idea.


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## Holmz (Jul 12, 2017)

Theslaking said:


> You're right! Changing the blinker fluid is a great idea.


All I see here are theories, including mine.
The OP can determine (with all the other noise) as to whether there is any useful information to his problem.

But the fellow's post that I linked to was reasoned.
I am happy to discuss which part(s) of it you believe may be 'magical'.

Obviously I am finding your broken wire theory bewildering, as I cannot understand how a broken wire can carry "too much" current?


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## Locomotive Tech (May 23, 2016)

OK The two things that stand out to me the most in all I have read here are;

Lighting circuit dimming only....some alt whine?

The issue "goes away" when running soley on the battery.

Try this, see if the backlight illumination on the HU dims in concert with the Batt. only scenario and Engine on scenario. I fairly confident at this point that your issue is only in your lighting circuit. Here's why

I think the reason you do not see dimming in Batt. only is that the battery is supplying ample current and voltage @ 12 (+/-) whatever the battery is supplying. With the engine on, the alt. is supplying added voltage above the battery's capabilities.

I am willing to bet that your headlights are brighter with your engine running as the alt is supplying added voltage, you can test that.

I am now going back to a weak ground in the lighting circuit. You seem to take care when replacing headlamps, kudos!, I am now in "Theslacking's" camp, the headlight switch, it could be dirty, worn etc. The added voltage from the alt. is overcoming the weak nature of the switch.

To prove this, if you are confident in your skills, jump out one headlight to a constant "hot" and negative from the battery, if that headlight does not dim with the tunes turned up, you will know that you need to go through the lighting circuit, source through the switch through the circuit wiring/connectors. I would go to the switch, gets used the most.


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## RockamyZ (Apr 29, 2017)

Fwiw, high current doesn't flow through the switch on this model. It controls the relays. Just saying. Also on these trucks if you have a poor ground, all kinds of weird chit occurs which leads me to believe a supply problem.
My 2000 Silverado has the smaller alt with newer battery and have no problems. Worked on a 2003 Silverado with flickering headlamps, push the brake pedal and the cluster stops working, relays clicking away etc. Poor body ground was culprit. Doubt that's the problem.
Is this truck a typical salt belt truck? Have you had a full diag scan of all modules?


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## Locomotive Tech (May 23, 2016)

If "high current" doesn't flow through the switch, then the current will flow through a relay. If the switch activates a relay, then go there. 

I doubt there is a supply issue, the dimming does not happen when only operating on the battery. Ground or weak connection is what I am thinking. he has no issues with the supply to the audio.


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## RockamyZ (Apr 29, 2017)

Possible Locomotive Tech; hard to dio without the car in front us. Need to use all the senses. I would like to be more useful here because I don't know squat about sq sound but 
could fix their truck in a jiffy.


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## Holmz (Jul 12, 2017)

RockamyZ said:


> Possible Locomotive Tech; hard to dio without the car in front us. Need to use all the senses. I would like to be more useful here because I don't know squat about sq sound but could fix their truck in a jiffy.


That is why I posted the link on post #24.

I am not sure how one tells without an oscilloscope...
Also not sure if they are dimming or going brighter if the alternator is lagging in phase. Hence the idea about tones or music with constant bass notes.


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## Theslaking (Oct 8, 2013)

Holmz said:


> All I see here are theories, including mine.
> The OP can determine (with all the other noise) as to whether there is any useful information to his problem.
> 
> But the fellow's post that I linked to was reasoned.
> ...


QUOTE=benny z;5090778]i'd just try changing the blinker fluid...[/QUOTE]

I was just making a joke about a line in the link you posted. Relax. This supposed to fun. 
If a wire was carrying to much voltage we'd have a headlights to bright thread! I'm saying that a relay or regulator may not be be passing enough due to fault or break. However that is all mute (when related directly to headlights) because he said it's all the lights and dashboard.


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## Locomotive Tech (May 23, 2016)

I think that "Theslacking" is not meaning a complete broken wire "open circuit", but rather a situation where "Strands" of a wire could be broken, could be a weak connection/contact. 

The logic is, Current is directly proportional to Voltage and inversely proportional to resistance. So the added resistance at a weak ground/switch/contact/termination, causes a drop in current. With the engine running, the headlights are getting a bump in voltage from the influence of the alternator allowing a slightly greater amount of current to flow through the weak spot, but as the audio system peaks those "extra" volts are being consumed by the audio system through the batt. the battery can react faster to demands than an alternator as it has a far greater capacity in reserve. an alt. has to react and as the demandload on the alt changes rapidly to the beat of the drums, I would suspect that the alternator is not supplying the added voltage fast enough and the vehicle electrical system is falling to the lower battery voltage. 

It would be interesting to see if the OP would verify the dimming intensity with the engine at high idle? 2500 - 3000 RPM's, I bet the dimming will be less as the alt is already spooled up. Suspect that dimming will still be present due to the reaction time of the regulator, but less at high idle as opposed to idle.

I don't think scoping the alt will tell you much other than the alt is doing what it is supposed to be doing, remmember, OP stated that current and Voltage are stable (engine on and off), at his audio connections.

If the OP wants, I will send him my scope or I have an SSTDR which would definitely show any spikes in resistance, and show how far away (in inches) from where the device is connected to any spikes in resistance in a circuit. If the vehicle is equipped with a headlight relay, then you would connect the SSTDR to the No contact of the relay where the B+ is and then to the (-) terminal of the battery. This will map the entire circuit and will even show the increases in resistance at each connection or termination throughout the circuit. I doubt the OP would want to fork over the shipping or the insurance on the SSTDR ($10K device), but I will loan it if he wishes.

I would start at the relay, change it, fairly cheap, and check every connection from there in the entire circuit


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## orion0469 (Oct 18, 2017)

Thank you all for you input. I have my saturday planned out.
the link from Holmz is assuming it is Only the headlights that are dimming.
So heres my plan.
1. Replace headlamps. 
2 replace all relays associated with the starting and charging system.
3. run direct power and ground to battery and switched to fuse block.
4. Check for issue.
5.If issue is resolved work backwards on the leads. 
6. attempting to isolate the voltage drop will be very time consuming.

ok so heres another question.
If my lights are off. and the issue still occurs in my interior lighting i can rule out a grounding issue with the headlights right? 
The backlight for the radio does Not dim. never thought to notice that.
Just dash illumination, overhead interior light, bed light, headlights and running lights. Headlights do no brighten with engine on or off. 
Mind you this is a brand new custom build alternator. 
"D1AD244HD200	New 200 Amp SINGLE BRIDGE RECTIFIER Delphi type AD244 Series Alternator w/ Heavy Duty Bridge Rectifier. This unit is built in the USA with NTN bearings which are the OE Bearings used by GM, Heavy Duty Bridge Rectifier inside the Alternator rated at 210 amps,Stators come out of Georgia, Heavy Duty Voltage Regulators from OE Supplier and all top Quality Components. This Single Rectifier unit does not have the extra Rectifier box as shown in the picture. Singe Rectifier Alternators installs just like normal without the extra work of installing the remote Bridge Rectifier box. Total Rectifier rating is 210 amps" Rectifier is self igniting and using 75 amp diodes.

Price comparison to mechman who uses foreign parts is 150 dollars 
National quickstart has been my goto alt place for years.
anyways

Loco I believe you got a point but the only thing is these GM systems with RVC dont care about RPM. from 2005+ all GM vehicles now have this. 
It acts like it never goes into charging mode. I have no way of seeing that. I may stop down to my friends shop and have him take a look. he also has a old school O scope I can probably use. 
If my Cap with engine on sees 14.7 to 14.9 with radio low and only drops 1 volt when bass hits down to 13.5 the Amp and voltage draw from what I understand should not be a large enough draw to cause this.
I can unplugg the alt and the truck still runs no dimming. plug it in..dimming.
soo It has to be between the BCM and ECM. But what draws power related to the radio? (which has its internal amp disabled) is it possible there is a grounding issue that is drawing across something there?
What do you think?


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## orion0469 (Oct 18, 2017)

oh and btw Brewmaster. Before I replaced the Alt It was only drawing 90 amps under full load. bass hits werent seen due to the type of device we were using..loadtester from autozone. everything passed. 14.4 volt constant 90amp high read.


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## brewmastr (Jul 3, 2015)

orion a load tester from autozone does not tell you anything going on with the vehicle its simply just putting a nominal load on the alternator to simulate a charging load and reading the output. An amp clamp will be the revealing device on what your vehicle is actually demanding from the alternator.

I run an Audison 5.1k and Audison AV Due in my system, when the bass hits hard i will see 210-220 amps from my vehicle with everything turned on like seat heaters and defrost. My vehicle has a 220 amp alternator so honestly i do need a high output alternator as I would like my charging system to have some headroom however I have not really had issues thus far, If i had halogen headlights however i sure would. That is just an example of what we are after checking here though. I would recommend this tool and checking what your amperage draw your vehicle is demanding Sears.com


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## Locomotive Tech (May 23, 2016)

Ok I see a little clearer, but from what I understand the RVC should go into the charging mode when the battery is below 80%? or headlights are on, WOT, a few other things I can't remember.

If you like I can send you the Fluke meter (attached picture). Its works well, it is the same as a clamp meter/amp meter, but you can undo the loop, wrap it around the target cable, tie wrap in place. Then you remove the display and then drive around. You should see the current increase under WOT and the other scenarios. The display is a wireless connection to the measuremnet side (connected underhood)


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## Locomotive Tech (May 23, 2016)

OR! if you are dead set on throwing a scope on the alternator, I will sell you mine for $300 shipped.


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## Holmz (Jul 12, 2017)

orion0469 said:


> oh and btw Brewmaster. Before I replaced the Alt It was only drawing 90 amps under full load. bass hits werent seen due to the type of device we were using..loadtester from autozone. everything passed. 14.4 volt constant 90amp high read.


WTF? 
The old alternator worked fine-n-dandy, and now the new one now dims with the subwoofer beats?
I am starting to think that if the alternator was changed coincident with the lights flickers, then it may also be the causal mechanism...

Just because "The big three" was done does not mean that it was needed, nor that it would have helped... And in this case likely the cause of the dramas.

---

So what to do now?

Pull up at night near a wall.
Verify that the beats make the lights flicker.
-
Turn off the engine... The lights should dim a bit - take qualitative note of it or use a light meter.
-
see if the beats cause the lights to flicker. the same, less, or more.


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## Locomotive Tech (May 23, 2016)

HUH? This happened after the OEM alternator was replaced??? Did I miss that earlier in the thread??

Now that's something that is very interesting!!!!


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## Holmz (Jul 12, 2017)

Locomotive Tech said:


> HUH? This happened after the OEM alternator was replaced??? Did I miss that earlier in the thread??
> 
> Now that's something that is very interesting!!!!


Well if the new alternator is 200A and the old one was 90A, then I would expect that the inductance of the windings alone will lower the bandwidth or make the time constant of the control circuit longer. And the beats are likely pulsating the required inrush current like a kid on a swing with legs pumping at the same rate...

This is also why I suggested the SW tones combined with the volume knob as a better test of raw current draw versus the inrushing/pumped current needs.


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## Locomotive Tech (May 23, 2016)

I still don't understand? If the headligths are ON, the RVC should be in charge mode? right? 

If the OEM alternator was solid and the "quickstart" unit is not.....then there might be something there. Aftermarket alternators have been used in systems with 5x's to load that the OP is using.

OP, you need to ensure that the RVC system is working as intended and elimate the RVC/BCM issue. I know that you believe that the RVC doesn't care about alternator RPM, but say that to those dreadful SPL folks who run undersized pulley's to gain alt. RPM at lower engine speeds. 

I still can't see way through that the OP has stable voltage and current at is amplifier and not at the Lighting circuit. 

Your HU backlite doesn't dim because it most likely has its own regulated power supply.


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## Locomotive Tech (May 23, 2016)

Let me know if you want to borrow any of my test equipment. We are here to help!


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## Holmz (Jul 12, 2017)

Locomotive Tech said:


> I still don't understand? If the headligths are ON, the RVC should be in charge mode? right?
> 
> ...
> I still can't see way through that the OP has stable voltage and current at is amplifier and not at the Lighting circuit.
> ...


I am not saying with certainty that it is the alternator, but I am pointing out that it is a possible mechanism if it is slowly adjusting to the load, and the load is quickly bursting inrushes of current.
So I think that without having a way (oscilloscope) to look at the voltage in response to the load then it makes it difficult.

The other way to deal with the lights then would be a diode feeding into a capacitor for the lights... Or... second battery close to the amp.

(Good point on the head unit... It is probably full of capacitors and regulated power.)


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## bassace (Oct 31, 2011)

Do you experience over-voltages after a sharp bass response as well with your voltage sag? 

I wonder if you have a voltage regulator lag. If that is the case, then I would expect no dimming on continuous bass and dimming(followed by an over-voltage) on sharp transient bass notes. 

An old battery could be drawing more trickle current from the alt than normal, but with a 200amp alt, I don't see that as an issue for you.

When I mean over-voltage, I refer to higher than regular alternator voltage.


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## DeltaB (Jun 17, 2017)

Before you go through a ton of throwing parts at your vehicle, insure these 2 simple things are done.

One, make sure you have a large gauge cable from the battery negative terminal to the body itself is in place. And second, another large gauge cable from the block/head of the engine to the body/firewall is in place. Make sure you have no paint on either that is preventing continuity. Insure amp is grounded to the body close to it's install point. Test again.


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## Holmz (Jul 12, 2017)

DeltaB said:


> Before you go through a ton of throwing parts at your vehicle, insure these 2 simple things are done.
> 
> One, make sure you have a large gauge cable from the battery negative terminal to the body itself is in place. And second, another large gauge cable from the block/head of the engine to the body/firewall is in place. Make sure you have no paint on either that is preventing continuity. Insure amp is grounded to the body close to it's install point. Test again.


Jumper cable systems an take care of points #1 & #2.
WRT #3... There is no way a bad ground on the amp would result in too much current, so I think we can dismiss that on general electrical principles alone.


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## DeltaB (Jun 17, 2017)

Holmz said:


> Jumper cable systems an take care of points #1 & #2.
> WRT #3... There is no way a bad ground on the amp would result in too much current, so I think we can dismiss that on general electrical principles alone.


The body itself provides the least resistance and is the best conductor for amp ground.


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## Holmz (Jul 12, 2017)

DeltaB said:


> The body itself provides the least resistance and is the best conductor for amp ground.


What are you saying?
That the electrons get into the amp causing the lights to dim because they cannot escape back to ground?


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## orion0469 (Oct 18, 2017)

Ok Saturday was a bust. 
few things i have found out.
1 sears is out of business. cant buy that tester locally. will try a couple places tomorrow. Thank you.
2. its not a ground issue. I bypassed the chassis wiring harness and ran power straight to the headlamps and ground. I unplugged the Generator battery control module. I Isolated the entire stereo from the vehicle chassis wiring.

testing purposes only fyi. so in theory. the alternator and battery and stereo and the headlamps are on their own circuit..(yes the relay is in the loop).
Lights dim with bass hits.

Recap for those who missed my posts...
new 200 amp alternator. Big 4 with 0 gauge done. New AGM duralast battery. 
60X4 600X1 RMS amp. 1Farad Cap.

Spoke with a master certified ASE mechanic. 
There is no fix for the RVC systems in GM vehicles.
Charge mode does not come on with lights on.
It is a gen IV system. It has a Lighting mode that raises the modulation spec for IDLE speed. basically raises the min output voltage to 14volts +

The issue is that the system Does not respond to voltage drops.
normal pre 2005 charging systems and 4 pin charging systems are ALWAYS charging.
these do not. So. im back to square 1. 
Service bulletins from GM (ironically do not include 2005 silverado 4.3L ) 
It can take up to 10 seconds for the RVC system to respond to a low voltage 
That's why the Cap does nothing, It cannot even charge the cap for 10 seconds. 
some of their stuff is confusing to me though.
they say that while this is in idle or lag mode the system relies on the battery to maintain system voltage. if the voltage drops below 80% it then goes into charging mode. This doesn't occur when the engine is NOT running. 
some say unplug the alternator because the rectifier is suppose to be self igniting. haven't tried that.

but 6 hours of trying to look for some sort of voltage drop in the lighting circuit provided 0 results. 

mechman makes a inline module that adds a resister you can adjust that increases to output voltage of the alternator. but it only works on 4 pin alternators and no I cannot swap due to the RVC system attached to the TCBM and ECM.

I am still not buying these results.

I have spent too much money and too much time to accept that GM has implemented a system that literally prevents people from adding aftermarket systems into their vehicles. that is just ridiculous..
BTW I know of 3 other people with silverados same year with this Exact same issue. and the local Custom sounds guy has one. yet he just installed a 2500 watt system in one with all stock equipment and it has not a single issue. voltage gauge bounces a little thats it.
I did get a response from one of the other forums I posted to 4 months ago.
They build custom audio systems in Vegas..
Literally no ****..guy tells me to go All LED. LED headlights and interior lights. 
/facepalm.

I am missing something. 
So Sunday I am ripping it all out.
I am removing the door chime module 
I am running speaker wires directly.
the only connections on radio will be power ground and switched directly to battery.

Thank you all for your input. 
I will keep you posted as to what the results are..
Btw I did have a friend use an Ammeter its drawing 140 total amps and 70 on the power lead to my amp on most bass hits. remember I don't even have this thing running half power. Its only fused at 100 
the stock alternator was 105 amp for the 4.3L so replacing the alternator with a 200 amp was a good choice.

If you all have Any tips ideas suggestions please keep them coming. Once I find the solution and I mean an actual fix. I am making it public. on every venue I can find even if I have to shout it from the rooftops.

I wish I was your neighbor Loco Id drop this off with you...

PS: Holmz you are correct. The system Does recover some but not enough to make it stop. constant 80HZ tone Dims lights but they do not return. an oscillating tone from 50HZ to 12MHZ system recovers once the Subs hit the 120HZ Xover point. Local sound shop Verified conditions. I did not do these tests. sorry if I left that out. This system has been thoroughly tested by 2 custom sound shops and tuned. They also have multiple vehicles with this same issue. They say just live with it or play music with your lights off.
I look like god damn disco ball driving down the road at night.


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## MikeS (May 23, 2015)

Try rear defogger switched on or other accessories one by one if it makes difference.

Does yours have the battery current sensor?


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## Holmz (Jul 12, 2017)

orion0469 said:


> ...
> I look like god damn disco ball driving down the road at night.


I would send you some music, but i was never into Disco and the Mrs stuff is on vinyl.

How about a regulator to send something like 11, 12, or 13 V to the lights?
Do you have the old 90A alternator?


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## orion0469 (Oct 18, 2017)

Hello All. Update. 

I have found 90% of the issue.
It took me having to completely remove the entire system to discover the problem.

This entire Time I have been testing this, I have been connecting and disconnecting the connections at the battery that I had using side post terminal extenders.

we all know these.

What the problem was I had tightened the negative battery post as tight as I could. what I didnt notice is the plastic cover had sheared off somehow and was blocking Full contact of the negative battery terminal to the battery.

with partial contact I was testing the system using the extended posts which of course had perfect voltage. 

but was NOT happening was the Ground loop isolator that the BCM uses to read Voltage draw on the system seeing normal voltage flow. because of the partial connection to the battery it was not seeing the draw from the amp. therefore would never allow the alternator to go into normal charging mode.

When I removed the terminals I also discovered that the post terminals were stripped and were not actually tight. How did I miss this? I think the last guy who tested this part of the system did this but I cannot be sure. I would have immediately fixed this. 

So. wrap up. 
Items I have replaced in my quest for a solution.
In order of what I did starting with First thing I checked 

1. Battery; old walmart special. Replaced with Duralast Gold 1000 cca, New brass terminals with externders.

2. All new leads. 4AWG lead free pure copper cables to amp. and 9 wire shielded leads to speakers from amp. New Grounds less than 16 inches from AMP with triple foot (grounds with 3 self tapper holes) Thanks to Local Audio works shop.including new fuse holder with 100 amp fuse.

3. Big 3 plus 1 using 0 gauge wire wheeled and sealed at all points to engine and chassis.

4. Replaced original 105 amp DG Alt with a Heavy duty 200 amp Alt with 75 amp rectifier bridge. (heavy duty) 

5. 1 Farad Cap. 18" from AMP in parallel.

6. all new lighting components. new headlamps relay and switch. tail lights interior light marker and turn signal lamps.

7. Grounded headunit to chassis direct. (not using factory ground in harness)

All of this and was still getting the dimming

After returning to the start. Literally removing everything minus the alternator.

8. Replaced the duralast gold with a Plat AGM 
Fixed the Terminals. 
(I also Moved the other leads away from the Groud loop terminal ) 

No longer Dimming. (Slight under full power) 

Voltage meter in dash now reads 15.6 while cranked to 25 out of 35. sub full power. 

Cap reads same. Voltage showing hit on cap but never goes below 14.7 

I have attached photos of my battery connections as they are now.
notice the negative terminal Does Not have the plastic cover anymore.

Thank you all for your input.

I apologize to the person who said to check the battery. I had Just replaced the damn thing..Twice! first one the positive terminal had a Crack around the side.

Please let me know what you think?


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## Theslaking (Oct 8, 2013)

Glad you got it fixed. Electrical problems suck.


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## Locomotive Tech (May 23, 2016)

WOOHOO! This is fantastic news! I was gonna PM ya to see how it went!!!! Very happy for you my friend!! 

You wiil now be one of the better sparkies in your neighborhood!


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## JH1973 (Apr 21, 2017)

gijoe said:


> Wow, with that amp you don't need a cap, high output alternator, or big 3. That amp will run off of a moped. Maybe take all of the unnecessary junk out of the equation, starting with the cap.


LOL...Exactly what I was thinking.I'm running 2 amps at a grand total of 850w and a DSP in a Nissan Sentra with stock alternator.Doesn't even budge the electrical system.


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## DeltaB (Jun 17, 2017)

orion0469 said:


> Hello All. Update.
> 
> I have found 90% of the issue.
> It took me having to completely remove the entire system to discover the problem.
> ...


It's why I said, with dimming lights, always start with the negative terminal and the connections to the body. I'm glad you pinned it down.


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## gumbeelee (Jan 3, 2011)

I just read pretty much this whole thread. If I were the OP and I had this to happen I would have lost my mind, U have WAY MORE PATIENCE THAN ME!! I cant imagine going thru all of that to find out the battery was the problem. Well I am glad u finally found the problem.


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## bassfreak (Apr 11, 2007)

what is the voltage when the dimming occurs?


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## bassfreak (Apr 11, 2007)

orion0469 said:


> Hello All. Update.
> 
> I have found 90% of the issue.
> It took me having to completely remove the entire system to discover the problem.
> ...


I cannot find the copper battery post i bought anywhere. I'm pretty sure it was from dropping hz. you need to get one. you are loosing alot of conductivity stacking connectors like that..


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## bassfreak (Apr 11, 2007)

https://www.droppinhzcaraudio.com/content/sky-high-car-audio-4-20-copper-battery-terminal


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## Chevytruck_83 (Nov 3, 2017)

Sometimes its best to step away and let a fresh set of eyes take a look. As an installation manager I realized that when someone cant troubleshoot their own mistake its usually something the take for granted and overlook over and over but someone else picks up right away. Im still a little confused as to why the lights only dim when it was running. if it was a combination of bad connection and battery i would think it would have been amplified without the alternator source for power.


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## Sine Swept (Sep 3, 2010)

A few tips I can give. I would nut / bolt any grounds, self tappers, no matter how many can come loose. I use hex cap bolts with a star washer and nyloc nuts, never seen one loosen up.

I also second the adding of a direct ground run to an unfused distro block to feed the amps. Do not attach this wire directly to the battery. Hook it up at the same point as the negative to body. This way when you pull the negative off the battery it will not try to use your new ground run as a new ground path from your battery straight to the amps. More like a worst case scenario but things happen. I have seen and used batteries with top and side posts, leaving that free ground lug on the battery as a possible hook up for the direct ground run. If you have both a direct ground to one post and a body ground to the other, then remove the body ground, you will then be grounded to the body through the amplifier!

If you are going through all the trouble, why not another 15 feet of 1/0 cable. It might save you that extra 10% you are missing. The reason the dash has a voltage drop is because your amplifier circuit is causing the system to have an overall voltage drop. If the amp drops less, so does everything!

Look at SPL cars that use 10 runs + and - just to keep voltage drop low enough to maximize the power from a single (or whatever) battery.


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## Rocky98Formula (Jul 13, 2017)

orion0469 said:


> "D1AD244HD200	New 200 Amp SINGLE BRIDGE RECTIFIER Delphi type AD244 Series Alternator w/ Heavy Duty Bridge Rectifier. This unit is built in the USA with NTN bearings which are the OE Bearings used by GM, Heavy Duty Bridge Rectifier inside the Alternator rated at 210 amps,Stators come out of Georgia, Heavy Duty Voltage Regulators from OE Supplier and all top Quality Components. This Single Rectifier unit does not have the extra Rectifier box as shown in the picture. Singe Rectifier Alternators installs just like normal without the extra work of installing the remote Bridge Rectifier box. Total Rectifier rating is 210 amps" Rectifier is self igniting and using 75 amp diodes.


Hi, I've been closely reading up on your alternator thread. I've got a 1998 Firebird and I recently swapped my stock C130 105amp alternator with a oem 4 pin AD244 factory rated for 145amps. I am having a lot of issues with voltage fluctuations on my battery gauge. If I turn my music up with some dynamic tracks (single Alpine PDX v9 amp), I can get the car to stutter and almost stall at idle. The fluctuations (and light dimming) are there even if I press the brakes or have my turn indicator on though they voltage swings are far less than when my stereo is full tilt. I am starting to think the issue is the rectifier or voltage regulator because it seems to be the transient loads that cause the needle to move but the voltage will quickly recover right after. My original alternator was on the way out and I opted to upgrade to the AD244 knowing I might be upgrading the stereo in the near future. When I first installed the AD244, I had an intermittent short with water in one of the tail lights that may have damaged the alternator VR.

My question for you was you mentioned the HD alternator you purchased. For these reman units, are all the windings new as well? I haven't purchased from this seller before and their site is thin on the detailed information. My other plan would be to just buy the HD rectifier and VR and swap them in myself.

I've done the big 3 and triple checked my battery connections after reading your solution. Everything looks good. My car uses the 4 pin style and only the L terminal is connected.


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## RockamyZ (Apr 29, 2017)

You need 5 volts on wire in the push-in connector of alt from the pcm to wake up the alternator. If not there or too low the wire may have high resistance, open or pcm is kaput. If voltage is there, the regulator is of poor quality and not sensitive enough or just a piece of after market ****. You stated having problems before new parts so I would go after the wiring first considering the vintage. Also possible is the new vr may need 12v trigger to wake up(wrong vr). GL


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## Rocky98Formula (Jul 13, 2017)

RockamyZ said:


> You need 5 volts on wire in the push-in connector of alt from the pcm to wake up the alternator. If not there or too low the wire may have high resistance, open or pcm is kaput. If voltage is there, the regulator is of poor quality and not sensitive enough or just a piece of after market ****. You stated having problems before new parts so I would go after the wiring first considering the vintage. Also possible is the new vr may need 12v trigger to wake up(wrong vr). GL




I did start having problems prior to swapping in the newer AD244. My original 105A alternator was bouncing all over the place. Turns out a tail light was full of water. Once I drained that and added drain holes, problem is gone. However, I didn't figure out the water in tail light until after I swapped alternators so likely the AD244 alt saw some shorts etc for a few trips. 

On my specific model year, the pcm isn't connected to the L input on alt. On mine, the 12v goes through the lamp indicator on instrument cluster and then to the L on alt. The other 3 pins are not connected so the voltage regulator is sort of in self regulate mode. I've been reading up on alternator lag but I don't understand how to get rid of it. Like is lag introduced by bad diodes or bad vr?

I'm continuing to clean, check, and replace grounds as I find them under the hood as well as under the dash. 


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