# Installing New Head Unit-- Will NOT Turn on!!



## and.i.craw (Oct 14, 2013)

I'm trying to install a new head unit into my 2004 monte carlo ls.. i already had an aftermarket HU installed but I am changing it again..

I dont have much experience with this but I matched all the corresponding wires together correctly and went to turn the car on to make sure it worked before putting dash back on and there was nothing.. no power at all... i have a scosche GM09SR/ GM09SRB harness with integrated chime in the mix.. i didnt install it with the first head unit but i remember they had some problems with the install before because of that thing.. 

the head unit doesnt call for an orange illumination wire so i taped it off at first but when it wouldnt start i put it to the red along with red and it still didnt worked. i checked the fuse panel by the door and checked all the ones i thought it could have been and they were all fine. 

i dont know what i could be doing wrong here.. i have all the corresponding wires matched up and theres nothing happening


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## [email protected] (Nov 7, 2010)

Does your dome light and cigarette lighters still work?


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## and.i.craw (Oct 14, 2013)

Yes.


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## and.i.craw (Oct 14, 2013)

I did not disconnect the negative on the battery like it said to...could that be the problem


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## [email protected] (Nov 7, 2010)

Can you take a picture of your dash and the wiring? Also, do you have a DMM?


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## and.i.craw (Oct 14, 2013)

i do not have a digital multimeter


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## and.i.craw (Oct 14, 2013)

the head unit states that 
yellow is a connect to the constant 12 v supply terminal
red is a connect to terminal controlled by ignition switch
the schosche unit states that
yellow is 12 v constant
red is 12 volt ignition switch
orange is illumination

i dont get why it wont work

i know in the picture the red and the yellow wires are not connected. they were connected at the time of posting this thread.


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## Lou Frasier2 (Jul 17, 2012)

have you checked the ground yet,check and double check all of the connections,


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## Alrojoca (Oct 5, 2012)

Connect the old hu to test it, maybe the new one is faulty or it blew a fuse during the install since the battery was not disconnected. 

Solder and heat shrink tubing or bullet connectors may provide less issues with connections


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## ccapil (Jun 1, 2013)

U really only need 3 wires for the headunit to turn "on" constant 12 volt (or memory), ground, and switched 12 volt ( should be 0v with key off and 12+ volts with key on acc. Get a multimeter and test every single wire in the harness and make sure when I match them up they are correct, they may not be red to red black to black etc. in my car constant 12 volt is red and blue in the harness and from my HU harness it's yellow. Check all ur fuses first otherwise u will read nothing on the multimeter


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## [email protected] (Nov 7, 2010)

When you turn the car on, does the relay click? That is what provides the radio with switched power, through that module..


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## and.i.craw (Oct 14, 2013)

I didn't blow the fuse on the HU cause I checked it. yea about the ground..it says to hook it up to the chassis of the car? I wired the ground from the HU to the ground of the harness cause tthat's how it was hooked up with the old HU.

where is the relay I'm listening to located?


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2004 Chevrolet Monte Carlo Car Radio Wiring Diagram


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2004 Chevrolet Monte Carlo Car Radio Wiring Diagram
Car Radio Battery Constant 12v+ Wire: Orange
Car Radio Accessory Switched 12v+ Wire: The radio harness does not provide a switched power source. Run a wire to the fusebox or ignition switch harness for switched power.
Car Radio Ground Wire: Black
Car Radio Illumination Wire: Gray
Car Stereo Dimmer Wire: Brown
Car Stereo Antenna Trigger Wire: White
Car Stereo Amp Trigger Wire: White
Car Stereo Amplifier Location: N/A
Car Audio Front Speakers Size: N/A
Car Audio Front Speakers Location: N/A
Left Front Speaker Positive Wire (+): Tan
Left Front Speaker Negative Wire (-): Gray
Right Front Speaker Positive Wire (+): Light Green
Right Front Speaker Negative Wire (-): Dark Green
Car Audio Rear Speakers Size: N/A
Car Audio Rear Speakers Location: N/A
Left Rear Speaker Positive Wire (+): Blue
Left Rear Speaker Negative Wire (-): Yellow
Right Rear Speaker Positive Wire (+): Blue
Right Rear Speaker Negative Wire (-): Dark Blue

that specifies that they are different but aa lot of those wires are only going into my harness and aren't coming out to wire the HU to. Like a tan wire there's no tan wire involved when connecting the HU to the harness. 

That schosche unit is supposed to be for my car , not for a specific head unit, right?


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## [email protected] (Nov 7, 2010)

The relay is the little black box that has the silver metal tab on it. there are 4 wires going to it, looks like yellow, black and 2 reds...


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## and.i.craw (Oct 14, 2013)

i do not notice the relay making and noise


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## ShaneInMN (Sep 27, 2013)

and.i.craw said:


> a lot of those wires are only going into my harness and aren't coming out to wire the HU to. Like a tan wire there's no tan wire involved when connecting the HU to the harness.
> 
> That schosche unit is supposed to be for my car , not for a specific head unit, right?


The aftermarket harness is vehicle specific, yes. Then the HU harness is to be spliced into that. It's the only way to make a vehicle specific harness without them having to be tailored to the different head units.

Go by what the wires are labeled as in the instructions for both harnesses, then pair up the corresponding colors and splice. I want to say my Alpine HU harness had a couple of colors that didn't match up, I just made sure to follow the labels first.


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## and.i.craw (Oct 14, 2013)

Should I just get a new harness with chime? It just sucks cause they're way overpriced.

do i even need that? Can I hook it up without that? All it does is ding if the doors are open and I can tell if they're open without the ding.


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## gijoe (Mar 25, 2008)

I would check the appropriate fuses in the cars, fusebox, not just the HU. If you installed it without disconnecting the battery, you easily could have blown a fuse. Check them with a meter, usually you can clearly see when they blow, sometimes though it's hard to see without putting a meter on them.


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## goodstuff (Jan 9, 2008)

What is the blue wire with white stripe going to in the second pic? Butt connector looks loose on the end I see bare wire. Also is that a chip clip in the dash? lol Have not seen one of those since the 80's.


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## and.i.craw (Oct 14, 2013)

That wire is going to the remote wire from my amp in my trunk powering two subwoofers


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## and.i.craw (Oct 14, 2013)

I went and bought a digital multimeter. I planned to just test all the fuses and the wires..and then end up having to buy a new adapter harness.. the relay isn't making any noises when I start my car..

right now my dashboard off still and since i wwork . 6 10 daysas iI havehaven't been able to work on it yet...but I noticed that my blinkers / turn signals don't work right now... I checked the fuse labeled as turn signals on the side of the dash and it wasn't blown.......

what does that mean? Do the blinkers just not work with the dash off? Should i check fuses under the hood as well??


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## mrvrsick (Feb 19, 2012)

I recently had trouble with a family car, a 2003 Malibu. 

If you redid the wiring, it's possible that you lost the 12v switched signal. Apparently, there is some difficulty with that on some GM models around that time period. I ended up running a wire for 12v switched to the fusebox, but only after I checked that red wire with a DMM and noticed that it didn't have a signal. Looking at the corresponding pin on the factory harness also revealed that it led to NOTHING. 

It's also written in your post: "Car Radio Accessory Switched 12v+ Wire: The radio harness does not provide a switched power source. Run a wire to the fusebox or ignition switch harness for switched power."

*Run a wire for the 12v switched.*


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## gijoe (Mar 25, 2008)

YOur blinkers are controlled by the hazard button. If you took that off with your dash, your blinkers won't work at all.


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## and.i.craw (Oct 14, 2013)

[email protected]

i already was using this harness with an aftermarket head unit. I unhooked that one to install this one. There was no wire being ran to the fusebox. How would you explain that?

Edit: the wiring harness from the car itself does not have a switched power wire, however the schosche unit (blue box) harness has a switched power red wire that is to be used for switched power to the head unit

also how would I even do that? Does it matter which fuse slot I run it to? And what cable would I use? Speaker wire?


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## gtsdohcvvtli (Aug 17, 2011)

Verify 12v at all times on that yellow. If yes power is good. 

After the harness is plugged in to the vehicle, close the doors, cycle ign on then off, then open and close the door. 

The blue box essential communicates with ur cars class 2 data network. The cars network is what essential tells the radio to turn on. The blue box looks for that command and turns on that relay to creat a 12v accessory for the aftermarket radio. 

The 12v acc is a RAP circuit. Retained accessory power. Essentially the radio will stay on until u open the driver door after the ign is turned off. 

3 problems that can be the culprit

1) no 12v constant on the yellow, check car fuses 
2) blue box is not communicating with the car. Bad box....or car lol
3) if box is communicating and provides 12v acc thru that relay, than can be bad radio


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## and.i.craw (Oct 14, 2013)

gtsdohcvvtli said:


> Verify 12v at all times on that yellow. If yes power is good.
> 
> After the harness is plugged in to the vehicle, close the doors, cycle ign on then off, then open and close the door.
> 
> ...


So for lack of better words you're saying that it might just need to be ran through those steps to be cycled back on?


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## gtsdohcvvtli (Aug 17, 2011)

Pretty much. They need to b initialized. But doesn't necessarily mean they act lifeless without those steps


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## and.i.craw (Oct 14, 2013)

what would iI check with the multimeter to check if the scosche unit is good or not? 

And so just leave the doors open.. plug in the harness and make all the connections..close the doors...turn car on...and then off...then open and close the door.andni hypothetically ifI turn the car on then it should be initialized and powering the head unit? If all fuses are good and there is power on yellow wire

edit: woops i was unaware that there is also a fuse panel on the passenger side.........and i looked up the diagram and there is one for "radio"....
so im hoping when i get off of work in the morning there is a blown fuse in the radio slot!!!


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