Hey folks,

Anybody run into this? I have a 2002 Monte Carlo SS. In fact, I just bought it today. When I turn the headlights on manually while the vehicle is running, the Service Vehicle Soon light comes on. There's no bulbs burned out, and all the fuses are good... Anybody have any ideas what would cause this?

Also, at night, when the "auto headlamps" are supposed to kick on,only the parking lamps turn on, the headlights do not. I wonder if the problems are connected. Maybe someone dug through the car and snipped a wire that turns on the auto headlamps, which makes the car realize that they're not working correctly when you have to turn them on manually? What do you think? For now, I have to drive around in the dark with the "SERVICE VEHICLE SOON" light on...yaay!

Thanks a ton!

 

Check the headlight switch

 

The switch works--only in the dark though. When I pull the switch to turn them on in the day, the parking lights come on. When I pull it at night (or when the sensor knows its dark) the headlights come on.

I ripped the dash apart looking for some possible bad wiring, and I found an aftermarket alarm was installed--but the wiring doesn't look to be bad. There's no corrosion or anything where the wires would have fallen apart, and all the connections are soldered. Does anyone have the wiring diagram for the BCM--that lists what color wire does what for all 3 wiring harnesses? And maybe know where wires go from there? Maybe I could put a meter to them and make sure that all the wires are good from the BCM all the way to wherever they're supposed to go...

 

It could be the alarm unit not working correctly
Do you know what type of alarm system it is
If there is a name, see if they have a website that might explain how the system works

 

It could be. I looked it up, looks like its an older alarm system with limited info on the company's website (of course, they only give detailed info to dealers/installers). It didn't come with a remote or anything. So I think today I'm going to open up the dash again, and rip it out and see how that goes. Wish me luck lol. I'll post how it goes.

 

Didn't work. I pulled the alarm, patched up and checked all the wiring, soldered all the connections back together how it should be, and still no luck. I checked all the relays and fuses that I couldn't check before once I had the dash ripped apart...the relays are good, but they're not switching because they're not getting "the signal" that they need to dump and turn on the lights... The switch checked out just fine--I wonder if something is screwed up with the BCM.

Any other ideas? I'm running out of them...

 

BCM was fried...took it to the dealer who didn't notice the problems during their inspection...but thankfully I brought the problems to their attention the day I bought it and they covered it all!