# Head Unit Grounding Question



## txbonds (Mar 10, 2008)

I'm in the process of soldering up the crutchfield wire harness that I received with my FH-P8000BT Pioneer. I've gotten everything soldered and head shrinked but the ground wire.

The wire harness adapter has a ground wire on it, but the Pioneer manual alludes to attaching the ground wire to the chassis via a screw to a metal point. Is this really necessary, or can I just solder it into the ground on the harness kit that uses factory ground wiring?


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## WrenchGuy (Jun 10, 2007)

I hook my power and ground directly to the battery. I've never had the Pioneer buzz issue ever and I'm on my 8th one. Thats me though. I believe the HU is putting out full potential this way.

Harnesses are just a convenience IMO.


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## jrwalte (Mar 27, 2008)

Since Pioneer has the wonderful easily blown PICO fuse problem where noise will travel through your RCA output, I'd suggest to do as it says, which will help prevent the PICO issue.


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## txbonds (Mar 10, 2008)

I just says to hook to chassis ground. The red wire says to hook to ignition switch 12volt dc. Yellow wire says to hook to constant power 12volt dc. Orange to illumination/dimmer.

So, does that mean straight to battery on power though? And does the factory harness ground not have a "chassis ground"?

I guess I'm just trying to determine if it will truly be worth all the extra effort of running ground wire to the chassis and power wire all the way to the battery, when I still have to tap into the factory wiring for the ignition lead and illumination lead. Make sense?


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## zero7404 (Jan 31, 2008)

txbonds,

be somewhat careful as to where you ground for your HU. sometimes a vehicle chassis is not really what it seems from an electrical point of view.....

i had an ordeal with my DRZ9255. partly because the installer wasn't as experienced in installing units that came with external dc/dc boxes.
anyway, the problem that arose was he installed per the instructions, grounding the dc/dc box to chassis, somewhere near the box. but that was a problem because BMWs don't have a consistent/level ground all throughout the body of the car. having to route the ground wire back to where the amplifier is grounded , AND grounding one of the unused RCA connectors to the chassis (at the amplifier ground as well) solved the issue.

just a heads up....


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## circa40 (Jan 20, 2008)

WrenchGuy said:


> I hook my power and ground directly to the battery. I've never had the Pioneer buzz issue ever and I'm on my 8th one. Thats me though. I believe the HU is putting out full potential this way.
> 
> Harnesses are just a convenience IMO.


+1...


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## txbonds (Mar 10, 2008)

So, if I'm understanding correctly, if I'm just going to throw it in there and use the head unit built in amps to power the 4 speakers, then I can probably just tap into the existing harness for all connections.

But, once I go to install my amps down the road, I should find a common ground point for amps, rca's and head unit, and run power constant 12 volt power wire for head unit to the battery just like the amps?

Is that a correct way of looking at it? All I'm doing now is just swapping out head unit for factory using head unit power. I won't be adding in sub and front stage amps for a while yet.


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## txbonds (Mar 10, 2008)

circa40 said:


> +1...



But you still tap into factory wiring for the illumination/dimmer, and the ignition switched 12 volt source correct? 

Just the constant 12 volt and ground run to the battery?


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## circa40 (Jan 20, 2008)

^ yes, thats what I did. Everything else is the same If you want to go that route)...I actually bypassed my OEM harness and found the appropriate wires elsewhere


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## txbonds (Mar 10, 2008)

Another question for you guys. If you hard wire your head unit directly to the battery for 12 volt constant and ground, do you also hardwire the ground on your amps to the battery rather than using chasis ground?


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## Oliver (Jun 25, 2007)

What stands out too me in this post, is if you intend to use HU power, then use a larger size wire for your ground to the chassis.

Reason , the IC will be getting extremely hot with all the subsequent problems of heat that goes with electronics.


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## txbonds (Mar 10, 2008)

I will be making sure my alternator to battery, battery to ground, etc are all larger gauge as part of my install, but if I'm understanding the suggestions being given to me, the chassis ground won't matter that much anyway if I truly am to route the ground wires on all this stuff all the way back to the battery.

I've always just used a solid chassis grounding point in the past. What I've done in prior installs is run say a 2 gauge strap wire to the actual chasis grounding spots or frame even, confirming they were solidly grounded items, and then run that strap to a wire terminal block, to which I then routed my ground wires to. 

Running everything to the actual battery ground terminal though seems as though it would pretty much aleviate any concerns over the chasis grounding situation.

Maybe I'm not understanding the suggestions properly.


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## jrwalte (Mar 27, 2008)

I think the reason most people don't do this is because the longer your ground wire the more potential for noise.


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## txbonds (Mar 10, 2008)

jrwalte said:


> I think the reason most people don't do this is because the longer your ground wire the more potential for noise.


So, it sounds as though the best way to avoid noise may be to run 12 volt constant to the battery, and run 12 volt negative to nearest chasis ground spot? 

Then maybe make sure I have adequate ground cables on battery to chasis?



Does it help to ground amp and head unit to same point? I was thinking, since I will be mounting my amps near to my head unit, that maybe I would just run a common larger 12 volt positive and mount a block for amps and head unit, then do something similar to chasis ground for all of the same grounds. Would this be a good way to go?


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## quality_sound (Dec 25, 2005)

With one exeption, I've always used the wires in the harness, even the ground. I haven't found any performance benefits of running new wires to the fuse block since, with the exception of the ground, that's where they're coming from anyway. Even the one time I did run new wires, I tried it using the harness and then with the new wires and NOTHING changed. It didn't run cooler, the display wasn't brighter, it didn't sound any different but since I had 2 single DIN units in there there was a LOT more room because I didn't have to deal with VW big ass quadlock connector.


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## BEAVER (May 26, 2007)

In my old lady's car I ran it through the harness and ran an additional ground to the chassis... just to be safe.


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## txbonds (Mar 10, 2008)

Interesting. I have been talking with another Toyota Tundra owner that just installed my same model headunit using the harness also, and he has had no problems or noise either.

It definately is much easier on me to just use the harness, as I've already soldered and heatshrinked all the connections up except the ground as I've been waiting on more input on this thread on that part. Surely the ground wire from the factory setup is grounded to a chasis ground somewhere if you traced it backwards. At least, that's what I would think anyway.

If thats the case, then it saves me trouble as then I've only got to worry about powering my amps, and grounding them.

Does grounding them amp and headunit at the same point supposed to help eliminate ground loop noise or something? If that's the case, then as Beaver suggested I could always just strap an additional ground to the head unit from this point if noise was incurred.

Part of the suggestions indicated using the direct wiring due to some pico fuse problems with pioneers I guess too.

Decisions, Decisions.


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## GenPac (Oct 29, 2007)

I'll throw in my useless 2cp  

If it was MY install, i'd use the factory harness ground. Just be sure to NOT HOT SWAP RCAs!
I'm not 100% on this, but i've searched about this problem here in DIYMA and it was pointed out that swapping and grounding out the RCAs, while power was/is applied to the HU, can cause the pico fuse to blow.

Oh, one more thing... if this HU as the RCA jacks as a removeable pigtail harness, make sure you _plug in the RCAs to the pigtail_, _then the pigtail to the HU_ -- LAST.


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## quality_sound (Dec 25, 2005)

If you're having noise issues you can ground the HU at the amp ground which can help in some cases but I wouldn't bother unless you run into that problem. 

"What-ifs" like that are the reason IASCA sucks balls now. You have to wire for contingencies that will likely never happen. Don't get sucked into that.


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## 89grand (Nov 23, 2006)

I've just used the factory harness with no issues. It sucks running wires all the way from the HU to the battery, I always have enough wires to run without adding more for no real reason.


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## txbonds (Mar 10, 2008)

Thanks guys. Made my life easier, as now I can at least just get the head unit plopped in to power factory speakers while I work on installing the other stuff. I've got some phased work to do with sealing the rear storage compartment and lining with sound deadner to mount my sub baffle board over, as well as the wiring for amps and other stuff, so at least I can just power factory speaks until I'm ready to swap over to outboard amps.

Then, I don't have to worry about wiring on head unit unless I have problems. I'll be sure to pull power before connecting any rca's also. Can't remember, but don't think they were on a separate harness.

Cheers.


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