All at once my beloved C5 has become a nightmare. A couple weeks ago I was asleep, all of a sudden the horn activates. Went out, hit the horn and it stopped. A couple hours later, same thing. Pulled fuse. Searched forums and found this is supposedly indicative that the air bag module needs to be replaced? Anyone have some info as to just what is wrong with the module causing this problem? Addtionally, the climate control display was out. Today I went to take the car to work on fixing the display...directions found on this forum...however battery was dead. I had picked up the car Wednesday at the dealer where I had the lumbar support fixed for the second time. Car just went out of extended warranty but dealer stepped up...since they replaced lumbar pump under warranty about 1.5 years ago, they did under warranty again. Kudos to Stasek Chevy, Wheeling IL. Anyway, when I picked up the fob did not operate trunk release...strange. Did work for doorlocks. Did not drive car for the time since. Today, batt dead. Put charger on, and the locks are cycling by themselves, hit trunk release and a humming/whirring from the fuse box / relays underhood. This is really getting annoying. Any ideas? Fob was OFF passive, however I have had a problem with the apparent passive activation even when switch is off in the past. Tried to search to find what wire to clip to permanently disable passive, but could not find it. This is really annoying since the car has been bulletproof for the first 4 years, and has suddenly gone to disaster in 2 weeks. Thanks for any possible help.

 

Hey Dan, thanks for the speedy reply. I am reading this as saying that you believe the crazy remote operation etc. is the fault of the drained battery. Do you think the initial problem on Wednesday -where the fob did not operate the trunk release- was battery related? I also don't know why it drained...there were no lights left on and car was parked in the garage.

I noted you said to make sure to drive the car...I do...it was only sitting since about 4PM on Wednesday until 4PM Sunday. I haven't replaced the battery yet, so after it charges up I'll pull it for a test and prolly replace it.

This compounds with problems to the winter beater...older Mercedes...that are also of the electrical ghost nature. As Paul SR. likes to say...makes me want to smash something.

 

Take a step back, tackle one issue at a time;

The majority of your "strange" issues (buzzing, key fobs not functioning properly, etc.) are a result of the battery issue.

The horn deal is a problem ($$). Basically the "membrane" (area between the vinyl and the air back itself) contains the horn "switch". Once a short develops (i.e. horn blaring away all on its own) basically you need a new center steering wheel center section. What I'm not sure of (haven't looked it up in the manual) is if you can simply replace the outer skin separate from the airbag component.

Don’t sweat these issues, just work through them methodically, you'll be good to go. BTW, the biggest "no no" here is letting your car sit w/o driving it; faulty batteries are a common result. So either drive it every few days, or get a battery "trickle charger" to keep it healthy.

 

Replacing the battery in my 2002 Coupe solved all kinds of weird issues.
The seat memory, radio, clock would all reset every time I would start the car. The gas gauge even would go to empty. Lights on the AC temp would go out. Battery never went dead or refused to start but when I replaced it all my problems disappeared.

 

I put a full charge in and drove it today. Seems to be better, other than now my oil gauge is pegged. Bad pressure sensor I gather. Sheesh, it all happens at once. At least the key fobs are working. I am going to clip the passive feature wire anyhow, seems like a dumb idea to me anyway. I can handle all the work of pushing a button. Hopefully I can get this all handled before I pull my hair out.

 

Scott,

I agree that a low battery voltage (and not as low as one might expect) will often lead to a myriad of electrical issues in these cars. I do recommend that you read the electrical sticky at the top of the page, as it has a plethora of information on C5 electrical issues.

I would also add this to all of that... if your Body Control Module gets wet from any source, it can cause any one of a number of electrical issues. I found that water had gotten into my BCM and resulted in the environmental control center light staying on all of the time (I discovered this only at night). This resulted in the battery being drained, which lead to a number of additional electrical issues.

The bottom line is I would look carefully in the foot wells for evidence of moisture and particularly in the passenger side foot well. Once I discovered the water (thanks to Bill Curlee!!) I was able to dry the BCM out and resolve all of my electrical problems, including the draining of the battery.

Good luck... GUSTO

 

When doing your battery, you might want to check the grounds, that car has a bunch of grounding points, which are poorly designed, they need to be cleaned, and silicone grease applied to the affected areas.

once you cleaned the grounds, things will settle down, You can have all the volts in the world, but without a ground nothing would work(even more on a corvette) steel bodyed cars can be grounded anyplace, but you have to go to the frame on a vette, to get a ground. you may look a a panel and notice its metal, but it may be fastened to glass.(electrical problems are easy, you need power, and a ground thats it)

 

Thanks for all the input. Did the climate control solder fix...worked like a champ. Put in a new battery just to be onthe safe side as I know the old one was in since I got the car about 5 years ago, maybe original. Next to tackle will be the oil pressure sensor.

Appreciate the help gents.