Hey everyone, until recently my Monte's been decent. I seem to be having a headlight not turning on issue. I saw a couple threads with the exact same problem Im having, but they never seemed to get any feedback or resolution, so let me see If I can word mine a little more in depth.

Last night I parked my car and put the parking brake on. Headlamps were working fine. When I got back in my car, started it up, and took the parking brake off, lights never came on. Markers, interior lights, and brake lights are fine. The only way to get any light is when I pulled the turn signal switch to activate the brights, but the switch would not click into on position.

I checked all DRL and Light related fuses, relays, and grounds. Seems to be no problem there. Bulbs are fine as they will turn on if I hold the High beams. Fog light DO turn on. There is no Daytime Running Lights in the day either. I replaced my dimmer switch about a year ago, so the last resort that I can think of would be the light switch on the steering column.

Any feedback, problem history and troubleshooting would be much appreciated!!

 

Is this a 6th gen? If u start it with the ebrake on, the lights wont turn back on until you release the ebrake and put it into gear. Its a safety feature to keep you from leaving the ebrake on

 

Nope, parking brake was off, had to drive home holding the high beam lever to have any light

 

I had a tech tell me it was most likely the BCM, and is equipped with a self diagnostics, does anyone know how to perform this?

 

On a side note, does anyone know of any other relays hidden around the car? Besides the ones in the 2 boxes under the hood, and the side of the dash on the drivers and passengers side?

Ive been researching this all day and so far it is very common in Chevy's in general, around early 2000's. One report was that there is hidden relays behind the cluster, can anyone confirm this?

 

Ill take a look on alldata for the location of the relay tonight and let you know tomorrow. Its been a while since ive fixed a headlight problem in a 2000+ gm vehicle but i know the last 2 i did work on ended up being the whole headlamp switch.

 

I just finished looking at the wiring diagrams. I can email you them if you would like. I'm ase certified in electrical so I will walk you through how I would test it. This is assuming you've checked all fuses with a test light. You can never trust looking at them because somethings they will look good even when blown. Basically the headlamp switch provides a signal to the bcm, which commands the relay to turn on, which sends power through the dimmer switch to the headlights.

The relay is located in the fuse panel on the drivers side of the dash. I would check the signal from the headlamp switch which should be a yellow wire at the headlamp switch plug. If thats good then move to the relay. If not then make sure the orange and red wires both have power and the black has ground. If that checks out then its the switch.

The relay is 4 pins, 1 is power, 1 is ground, 1 is signal from the bcm, and 1 is the output to the dimmer switch. Make sure it has power and ground then check the signal. If your not getting the bcm signal then the bcm or a bad wire is the likely culprit, if you are getting this signal then I would move on to the dimmer switch.

At the dimmer switch, check the black wire for ground. If thats good then turn on the headlights and see if you get power at the yellow wire. If thats good see if the brown wire has power when the switch is on low beam. If you don't have power there then the dimmer switch is most likely the cause. if you do i would suspect a bad wire to the headlights.

My guess is its either the switch or bcm. since you don't have drl either it pretty much rules out the dimmer switch because the drl circuit is separate from the low beams.

I hope this helps and i hope it didn't confuse you. i have a hard time putting things into words, lol. Actually before you start this check the sockets for the low beams. When I first bought my monte both low beam sockets were melted and would intermittently work. Let me know you you find

 

Alright Ill focus on checking the bcm then because I did check the relays and dimmer switch (which is fairly new). I also have a strong feeling its the BCM because in the research Ive been doing in the last couple days, the ones who have fixed the same problem I have, turned out to replace the bcm.

 

Before replacing the bcm make sure all of the power and ground circuits going to it are good. There are several and one bad one can cause problems. When it comes that time let me know and I can get you a pin out of the bcm connector.

 

Where could I buy a BCM?

Also do you know what places would be able to program the bcm if thats what it is? I know the dealership does it but I dont feel like spending $80/min. Would Pepboys and places like that be able to?