This is going to be a fairly long post so please bear with me. I have a 2005 Corvette which I bought new. It came with the 6 disc CD changer radio, which I did not care for. A few months after purchasing it I had an aftermarket stereo professionally installed. It is an Eclipse AVN5435. A few months after having the stereo installed, I received a notice from GM that they were changing OnStar from analog to digital. At the time, I was using OnStar so I had my dealer change out the OnStar module. Everything went well for a few months. One day I was in my garage and noticed my car had turned its headlights on by itself. I tried rotating the headlight switch but it would not turn off. I unhooked a battery cable and called my dealers service department. My dealer is 90 miles from my home and they made an appointment for me the following day. The next day, I hooked my battery cable back up and noticed the headlights had gone off. Since I already had an appointment, I decided to drive the 90 miles and hope the headlights would come on by itself during the trip. Well, they didn't and the service manager told me they could not do anything unless it was happening at that time. I let it sit in their garage for a coulpe of hours but they never turned them self on. So, I went home. A couple of months later, my car did it again. Again, I made a 90 mile trip and they were off when I got to the dealership. The service manager asked me to take it to a closer dealership, since it was still under warranty, the next time it happened.

Several months went by and it happened again. I got an appointment at a Chevy dealer 10 miles from my home. By the time I got the car to the dealer, it had turned the headlights off again. I left my car with then for 3-4 days and they called me and told me they had been able to fix the problem. When I went to pick up my car, I saked the service manager how they fixed the problem. He had the "mechanic" that "fixed" my car show me what he had done. When the headlights came on, he took his fist and banged on the floor above where the body control module was. He said that is how he got the lights to go off!! I thanked them and left.

Several months after this episode, I went to the MidAmerica Motor Works funfest and I had the opportunity to discuss the problem with one of the C6 engineers at a seminar. He told me it sounded like a body control module problem. By this time the car was out of warranty and I had not had the problem occur for quite a while so I did not do anything about the matter.

About 1 1/2 years later (just the other day) the problem reared it's ugly head again. I called my dealers' service department and told him that the C6 engineer had told me it was probably a bad BCM. He agreed that would be a good place to start. So, I ordered a new BCM. When it came in, I called the Chevy dealer 10 miles from my house and asked them if they could program and install the new BCM. They said they could. Yesterday, I took my car in to have the new BCM installed. The service manager told me before the install that that was not my problem!! He said the problem was the aftermarket stereo and an aftermarket security system which I had professionally installed several years ago. Since I had already purchased the BCM, I told them to go ahead with the install. About an hour later, they informed me that my car was ready. They had parked my car outside after the install so I paid them and left to get my car and go home. When I got to my car, the headlights were burning sitting outside in the bright sunshine. I went back in to talk to the service manager and he informed me that the only way to solve my problem was to get rid of all of the extra s**t that I have had installed since I bought my car. He claimed they had a lot of strange problems when people put aftermarket equipment on their cars. So, now the only way I have to turn off my headlights is to take off a battery cable or pull the fuses in the engine compartment.

It has been a few years since this problem first occurred, but it seems like it first happened a few days after my dealer changed my OnStar module. Is this just a coincidence? Can anyone help in this matter? I do not want to take out my aftermarket stereo! My installer informed me that he did not hook into the BCM for power to the stereo. Could it be the aftermarket security system? There seems to be several wires from it running to the BCM. I very seldom use the security system anyway. My stereo installer said he would unhook all of the wires from the aftermarket security system. But, I was already having this problem before I had it installed.

I have no idea what to try!! One of you experts, please advise me on what to try. Sorry this is so long!

Thanks,
Mellow

 

Only thing I can think of is that the interface module for your aftermarket radio is somehow telling the BCM to turn on the headlights.

 

I am not expert but it seems to be the issue may be with the new onstar module, OnStar has the cabability to turn on the headlights and since you replaced the BCM I would look in the direction on OnStar, I wonder if the next time it happens if it would be possible to temp disable OnStar and see if head lights go off?

 

It's happening right now. Can't turn the headlights off without pulling fuses. Where is the OnStar module? I'll try anything!

Mellow

 

Just pulled OnStar fuse. No joy! Headlights still on!

 

C6 headlight schematics are here: 1 2

I suppose it's possible that one of the relays can be getting stuck in 'on' position, but there's no real reason why they would just come on in the middle of the night without a signal from the BCM. Look under the fuse box for the pink/white wires at pin F1 of plug C3, trace those wires as far as you can to make sure they haven't rubbed a hole through the insulation (and occasionally short to ground, which would turn on the headlights).

It is the low beams and not the high beams, right?

Is it JUST the headlights, or headlights and all other parking lights also?

The radio interface module does communicate on the same serial data line as the BCM (the BCM is what tells it to turn on the radio), but it shouldn't be sending any coms out, only listening in on the other info being sent out by the car. Do you have any idea what module was installed? You may want to get a new one just to prove to the dealer that isn't the problem.

You can find all of the BCM plug pinouts HERE. I suppose it's possible the turn signal switch can be shorting out some how and telling the lights to come on.

With the schematics I linked to, a good multi-meter, and the headlights remaining on for no aparent reason, a good troubleshooter should be able to narrow it down to the bad component (or at least eliminate several good ones).

 

WOW Mark! Thanks for the great info. Yes, it is just the low beam headlights. No other lights are coming on. And I did replace the BCM. Now the headlights are staying on all of the time!! I have to pull the 2 low beam fuses to turn them off.

 

Take out relay 47, use a meter to check for resistance from pin M2 to battery [-] terminal (fuse box has labels on it like the game Battleship), it will most likely be in the single digits if your lights are staying on. (you can also just pull that relay to turn them off, instead of the fuses)

Then unplug connector C2 from the BCM (it's grey, look at pic 2/5 in the BCM link for shape of plug), with C2 unplugged check ohms from M2 to ground again. If it's open the BCM is telling the lights to come on, a dealer or someone with a Tech2 may be able to dig into the programming and see where that signal is coming from (I'm not really sure exactly how that works). If M2 to ground is still in single digit ohm range with C2 unplugged then one of the pink/white wires is shorted to ground.

Something else to try... If the radio interface module is causing this, pulling the RDO/S-BAND/VICS fuse in the passenger floorboard should kill power to it. With the module dead see if the normal switch can be used to turn off the lights.

 

Update: Yesterday afternoon I unplugged the relay #47 in engine compartment fuse box to kill the lights. After taking it out, just for kicks, I plugged the relay back in. Headlights did not come on!!! Started the car in the garage and headlights came on like they should. Backed the car out of garage in the sunshine and after a few seconds lights went off!! Pulled car back in garage and after a few seconds the lights came on. Rotated switch on stalk to turn them off and they went off. DIC says headlights suggested, like it should. Checked on car in garage several times last night and headlights were off!! It's been almost 24 hours since I made my discovery and everything is working properly. What the @^&*!( happened??

 

relay prly failing... i would replace just to cover ur self

 

100%, Replace that bugger

If it was a sticking relay, my only question would be what made it come on in the first place while sitting in your garage with the car turned off

 

This might not make any difference, but remember the headlights were on after the BCM was replaced. Could replacing the BCM have caused the relay to stick?

 

not really

 

Have any of you guys with after-market stereos had any problems like this?

 

I seriously doubt your problem has anything to do with the stereo mods.