05 GTO - Radio Problems! Very wierd

[Jcook]

2005 Pontiac GTO with U7191.

So my stereo may work today and not tomorrow etc. By not working i mean it is on but no sound. I have an aftermarket deck installed by me. I decided to swap back to factory while it was having one of its episodes. No sound from factory deck either. I took it to the dealer and as you guessed it the stereo worked that day. lol 15 minutes after i left the dealer the radio was dead again.

Also the fuses check out OK. The day i installed my Predator tune is the day the problems occurred. Is there anyway that the tune would in anyway affect the radio? I reinstalled the predator just earlier and i pulled the (3) radio related fuses from the car and still no sound.

Steps i used during tune install.
Removed phone from car. Radio turned off. E-brake pulled up to turn off DRL. plugged it in and installed.

[dbarden]

Hmmm, I really dont think you have a issue w/tuner, what you probably have is a loose ground somewhere......You'd be very surprised to know that there are alot of grounds in and around new chevys. Use a multimeter, check your decks ground terminal to body ground, you should read continuity, if you are using the stock speaker harness check those pins to ground also........Very important ground would be to check and also verify is the engine to firewall ground, check that one from the neg bat terminal to body ground, check from the neg term to the engine and from the chassis to the neg term they should all be continuity (0 Ohms) or less than 1 Ohm....Recheck all your wiring you hooked up during you new deck install, you might have overlooked something or will hopefully find the problem. Hope this helps.
Dan

[Jcook]

I never had any problems until i installed the tune. The exact say day as the tune install to be precise. It seems like when i remove the tune and take the car to the dealership the problem goes away. I get the car back and reinstall the tune and the problem will be back with that day or the next day. The radio usually doesn't cut out while driving, hitting bumps, etc. Typically the radio either works or it doesn't when i first get in the car. As in i can go outside this morning get in the car and it MAY or MAY NOT work. I leave work it MAY or MAY NOT work. It has only switched while driving maybe 5 times out of the 100 times i have had this problem.

[06MonteSS]

that is definitely not a tune issue... sounds like you have a wiring short somewhere... the tune has nothing to do with the radio at all...

and btw, you don't have to pull any radio fuses when installing any tunes.. the only fuse you should pull is the OnStar fuse, if you even have it.

[sharkzf6]

No way this is a tune issue.
FYI – if the ’05 GTO has a body control module (BCM), and it probably does, then you need to look into that as the possible problem. We had a guy on our Corvette forum install a CB radio on his '04 ZO6 and shortly thereafter the BCM failed. Long story short, anytime you add something (like a radio/CD/DVD) to a new vehicle, it’s something you must be careful of. Apparently it’s very sensitive and causes all kinds of strange problems when it malfunctions - like interrupting power to the radio power jack. Check into it …

[Jcook]

Where is this BCM located? Also the radio is on and the screens makes it seem as everything is OK, but without sound.

[06MonteSS]

could be under the dash, under the hood somewhere, under a seat, inside the door, who knows... your service dept. should know, and it would also be in the service manuals.

again, no sound seems like it's a short somewhere, or a loose wire, or a faulty amp, etc etc.

[sharkzf6]

Where is this BCM located? Also the radio is on and the screens makes it seem as everything is OK, but without sound.

Unfortunately I don’t know the answer to that question. In fact, I don’t know for sure that the GTO has one, however, I’d bet good money it does since it’s a more upscale performance vehicle. Contact your local dealer or check out the many GTO/LS1/LS2 forums on the ‘net.

As for your problem - if you have power but no sound I would guess you have a speaker ground issue. I realize the irony of developing a problem coincident with the DMSP tune and yet not having anything to do with it is puzzling and suspicious. Let me just say I have 20+ years experience troubleshooting electronic problems and I’ve seen this kind of "irony" many times.

Hope you get to the bottom of this soon. Good luck!

[dbarden]

Yes the vehicle does have a body control module(BCM), usually under the steering colum, usually with 3 plugs attached to it. Mine is approximately 4" X 6" X 1", The BCM is programmed for all you accessories etc., I added fatory fog lights and had to have it reprogrammed for them to work. I had an issue with a broken grond and the whole truck went south as far as all the wiring was concerned. The engine to body ground strap was broken and all the electrical grounds found a ground through the instrument cluster, was fine until the cluster shorted out, then all hell broke loose. The wiring in these new cars/trucks are very sensitive. It took me 9 days of electrical troubleshooting to find the problem. The BCM does control the radio, the power windows all the lighting and everything else imaginable. You need to get the wiring schematics for your radio(Sock) and verify all is ok, sharkzf6 is right. Trust me too, if and when you installed the new deck, was the battery disconnected, did you use a professional install kit from a reputable company etc. are all questions you should be asking. When I installed my new deck i purchased a female pigtail for the stock radio harness and wired into the new decks harness so it was a plug and play type of affair, no issues ever. I have the factory service manuals for my truck, let me look into them and get back to you in a couple of days, BTW most service manuals for new cars/trucks are over a foot thick per production model. oh do you have stock speakers or aftermarket and if so what is the impeadance of them, are you using the factory speaker wire hareness or did you run seperate wires.
Thanks
Dan

[Jcook]

My next steps are 1)disconnect battery for 10+ minutes and 2)install quick connect wire connections on all 4 speaker on the wire harness. I will disconnect all the speakers except one. I will keep plugging in more until the problem returns. This may narrow it down to a possible bad wire.

How is it possible for the BCM to control the sound coming for the head unit(factory or not?)

To answer a few of the questions:
1)oh do you have stock speakers or after market and if so what is the impeadance of them, are you using the factory speaker wire harness or did you run separate wires.
the only thing i changed was the head unit. the problem also occurs with the factory HU. So my wiring capabilities and quality of after market parts is out of the equation.

[sharkzf6]

My next steps are 1)disconnect battery for 10+ minutes and 2)install quick connect wire connections on all 4 speaker on the wire harness. I will disconnect all the speakers except one. I will keep plugging in more until the problem returns. This may narrow it down to a possible bad wire.

good plan ...

How is it possible for the BCM to control the sound coming for the head unit(factory or not?)

It's very unlikely if not impossible. Like I said, I believe you have a speaker ground problem.

To answer a few of the questions:
1)oh do you have stock speakers or after market and if so what is the impeadance of them, are you using the factory speaker wire harness or did you run separate wires.
the only thing i changed was the head unit. the problem also occurs with the factory HU. So my wiring capabilities and quality of after market parts is out of the equation.

Sounds like you have a good idea what's going on. My bet is the strategy you described above for troubleshooing will uncover the problem. Good luck!

[Jcook]

i sure hope it points me in the right direction

[dbarden]

The BCM doesn't control the sound output, so much as the theft deterent system built into the factory head unit, and I believe weather or not the unit will or will not recieve power or be given crucial wake up commands from sleep state etc.......Think of the BCM as Energy Star Compliant type device. Seeing as now both units have the same recurrent problem, eliminates the decks and possibly the BCM, your next moves will or will not uncover speaker or speaker wiring related issues. Should the need arise the dealer can test the BCM in car for you, I had mine checked out, $59.00.........Good luck, hope you find it.....
Dan