Mechanics

CHEVY HEADLIGHTS WONT TURN ON

2003 Chevrolet Monte Carlo

Electrical problem
2003 Chevy Monte Carlo 6 cyl Front Wheel Drive Automatic 150000 miles

Im having problems with my 03 Monte Carlo SS Headlights. The other night they were working perfectly. I parked the car and shut it off. When I went to start it up the lights didnt turn on as they usually do. When I manually attempted to pull the switch so that the lights would come on, nothing happened. The only way for the headlamps to come on is the pull the lever on the steering column in which the high beams came on, however would not stay on. All other light work, fog, interior, turn signals, brakes, etc. Just not the high/low beams. And this vehicle does have a day/night sensor that automatically turns on the lights.

I've checked my fuses, Relays, Bulbs, connections, and other common problems. The last thing I think it could be would be the light switch on the steering column. Any feedback/troubleshooting would be a great help.
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Seal0716
September 21, 2010.




Hi seal0716,

Thank you for the donation.

The headlights are controlled by the Body Control Module ( BCM) which is equipped with self diagnostics. Perform the following and let me know what you find.


http://www.2carpros.com/forum/automotive_pictures/192750_HeadlightDiagnostic03MonteCarloSS01a_1.jpg



http://www.2carpros.com/forum/automotive_pictures/192750_HeadlightDiagnostic03MonteCarloSS01b_1.jpg


KHLow2008
Sep 21, 2010.
Sorry to say but the 1st picture is very blurry and hard to read, is there anyway you could resize it or send it to my email?

Tiny
Seal0716
Sep 21, 2010.
Diagrams size are limited so I have forwarded a pdf file to your email address.

Hope it is helpful.
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KHLow2008
Sep 21, 2010.
Yes I can see it perfectly now, just gotta get a scan tool, thanks.

Tiny
Seal0716
Sep 21, 2010.
There are some sub-routines that you have to perform if it leads you there. Let me know what they are and I will get the files for you.

KHLow2008
Sep 21, 2010.
Its seems I didnt get any DTC's back, I only had one code and that was P0420

Tiny
Seal0716
Sep 22, 2010.
On a side not that may help diagnose this, lately Ive been having a lot of trouble with my a/c. I have dual climate control and only one side gets somewhat cool, while the other is hot. Ive vacuumed the system out, refilled, cleaned, etc. Could this also be a BCM issue.

For awhile before the light went out, I was also getting a " Highbeams Out" message on my dash, when the highbeams were perfectly fine. Hope this helps to diagnose a little better.

Tiny
Seal0716
Sep 22, 2010.
The HVAC system is not controlled by the BCM. Symptom indicates the air delivery is at fault and it could be a vacumn fault resulting in the delivery. Vacumn is derived from engine intake manifold. Check the vacumn hoses for kinking, leakages or blockages.

The other fault would be the Air Temperature actuator. They could be stuck and heated air is being mixed with the AC cold air.

P0420 is catalyst below efficiency and it can be a faulty catalytic converter, exhaust leakages or bad O2 sensors.

The " Highbeams Out " message indicates possible BCM fault. Somewhere there is a communication error.

Some scanners are not able to retrive other than engine trouble codes. Ensure the scanner you used can retrieve all other codes.

KHLow2008
Sep 23, 2010.

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