I tried to search for this but couldn't find the answer. Hopefully someone knows right off. Went to Carlisle this weekend and did lot of night driving.

The headlight motors on my 2000 c-5 don't work when the motor is running. Works when key turned on but motor not on. Lights go on like they should but doors closed. Twilight works as it should but doors don't open. If lights up with engine running and lights turned off doors stay open. So to put lights on I need to stop the car, turn off motor, turn on lights and go. Anyone know what it is?? When the motor is off lights go up and down and on as they should..

 

I'm trying to fix my own headlight problem on c4 but found this and it may help us both; on yours though, have you tried disconnecting the power, manually putting them up, reconnect power and then see? soundsl like they're 180 degrees out of sync somehow, I had that happen to one of mine when I reinstalled it.

Headlight Issue

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I was told by chevy dealer that to fix my headlight problem is something to do with the computer system and they will do it for me for $250. I think thats expensive does anyone knows what they were talking about. I installed a brand new headlight motor but when i turn the lights on the light goes up and down for like 5 to 7 sec and stops somewhere. Like i said the chevy dealor said its a computer thing.

Any help or guidance will be appreciated

Ramez


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08-26-2007, 01:02 AM #2
DeeGee
CF Senior Member





Member Since: Dec 2003
Location: Horncastle Lincolnshire, England

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The dealer is correct in one way. The BCM does control the motors but I don't think its a computer issue from what you've described.

Someone posted a guide on how to troubleshoot headlight motor issues. I'd give him credit but I didn't note who posted. Worth checking the connections as a first try if both headlights are affected.

First thing to check is the Headlight Actuator CONTROL module located under the passenger headlight on the front of the passenger wheel well wall. It translates the ON/OFF signal from the headlight switch/BCM to a RAISE/LOWER signal to the headlight doors.

Here's how the control module works. If you look at the headlight connector just behind each headlight (5 wires total). 2 are for Headlight Open/Close, 1 is for Low Beam, 1 is for High Beam and 1 is Ground for Low/High.

The 2 Open/Close wires are Lt Blue/Dk Blue for the Passenger Side, and Lt Green/Dk Green for the Driver's side.

Take the Driver's side for example, both the Lt Green and Dark Green wires always have +12V in steady state. If you have a DVMM, verify that both these wires are providing +12V even with the car OFF. Since they're both at +12V, the motor has a net voltage of 0V across it so it stays where it is.

To Open the headlight, the Dk Green is momentarily grounded by the control module (i.e. +12V on the Light Green, Grnd on the Dk Green). Conversely to close the headlight, the Lt Green is momentarily grounded. The control module may not be doing that either because it's faulty OR posibly the connector could be having problems. The first thing to do is try to access the control module and remove/reseat the connectors (there are 2 connectors, one on each side of it). You may be able to squeeze your hand under the passenger headlight when it's up but it's tight so the best way is to remove the access panel under the bumper and reach up.