Thursday, July 21, 2011

chevy silverado headlights will not turn off

It is located in the middle of the dash, up by the windshield. looks like a little black LED light, but obviously doesn't light up


If all checked ok, then problem is with BCM.The body control module (BCM) controls all llighting functions. The problem is in the BCM.

is there something covering the little sensor on your dash? If there is something covering it, your headlights will automatically come on since it will think it's dark. Here is a picture from the outside of the truck of the sensor



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dash tore apart and you could see the wire that plugs into the sensor.
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You can also disable the Ambient sensor.There is procedure.-------


Basically you will need a pair of wire cutters and a 1.5K ohm 1/2 watt resistor that you can get at Radio Shack. Electrical tape and possibly some wire nuts will work to wire in the resistor. You can solder the wires if you wish.

You may want to remove the neg. battery cable to assure you don't do any unwanted damage to the electrical system. This is not necessary, but a good precaution to take.

First locate the Body Control Module (BCM) which is under the dash, below the steering column. Laying on the floor, this should be visible without removing any dash panels. You should find a purple connector (C3). Unplug it.

Locate the white and gray wires (A4 and A6). white and gray . It doesn't matter anyway.

Clip these two wires that are coming off this plug (C3). Leave a few inches to work with. Tape up or place wire nuts over the other end of these wires that go up under the dash(they go to the light sensor). You have now removed the light sensor from the electrical system and is now just a dash ornament.

Connect the gray wire from the plug (C3) to one end of the resistor and the white wire to the other end. Make sure you tape up all wires to prevent a short. You should now have a gray wire coming from C3, going to one lead of the resistor and the white wire from C3 to the other resistor lead. Plug in C3 to the BCM and replace the neg. battery cable if you removed it. Start the truck and make sure the lights are off. Throw a dark towel or something over the light sensor on the dash and verify the lights stay off. Try your light switch that has probably never been used and that's it!


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