'02 Sierra Automatic Headlamps

AMH · October 25, 2007

2002 GMC Sierra.

Other than pressing the dome override button four times each time the vehicle is started, is there a way to disable the automatic headlamps? I have already pulled the relay for the DIR's.

Thank you Alan

Colorado Kid · October 25, 2007

Not that I know of.

The system turns the lights on whenever it doesn't see voltage from the photocell sensor on the dash, so removing the sensor would cause lights on at start-up every time. If you could somehow rig a light to shine on the photocell, that would keep the lights off. I don't know how much voltage it's looking for, but if you spliced the appropriate battery in place of the photocell that would kill the lights too. (They'd still come on if you turned the knob).

Personally I like the automatic headlights, and it's no problem to override them on the occasions when I need or want them off, so I won't be experimenting with my truck.

Colorado Kid · October 25, 2007

After a little more research:

Here's a link

AMH · October 25, 2007

After a little more research:

Here's a link

Thank you for the replies. The link did not function, however I dug a little deeper and found this link

http://www.gm-trucks.com/forums/index.php?...mp;hl=headlamps

I found a schematic for the '02 model, and the above link describes the same wire color pattern and BCM location. Will post the results in a few days. Alan

Colorado Kid · October 25, 2007

That's very strange. You found the topic I tried to link to.

AMH · November 1, 2007

I am pleased to report the headlamp modification was a 5 minute repair. The BCM was located under the drivers side dash in plain view. The purple connector was to the right, close to the center console.

Life was so much easier before I sold the '80 K10. Alan

Below is the text in it's exact form copied and pasted from the link mentioned in post#4 I DID NOT add a toggle switch as was suggested at the end of the article.

To disable the auto headlights you need a 1.5K ohm resistor (Radio Shack) and 2 Scotchlok Tap Connectors (Walmart).

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). I don't remember if white is A4 and gray is A6 or vice versa. It doesn't matter anyway. BTW - there are two gray wires in the connector. The one you want is the one farthest away from the white wire.

Tap the gray wire from the plug (C3) to one end of the resistor and the white wire to the other end. You don't need to cut the wires. Make sure you tape up all wires to prevent a short. You should now have a gray wire coming from C3 tapped to one lead of the resistor and the white wire from C3 tapped to the other resistor lead *. Plug C3 back into the BCM. 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! Takes about 5 minutes.

*You can add a switch here if you want. Just connect one end of the resistor to one of the wires in the connector (doesn't matter which one) and the other end of the resistor to one side of the switch. Then connect a wire from the other side of the switch to the other wire in the connector. This will allow you to turn Twilight Mode on and off.

stillen · November 1, 2007

I am pleased to report the headlamp modification was a 5 minute repair. The BCM was located under the drivers side dash in plain view. The purple connector was to the right, close to the center console.
Life was so much easier before I sold the '80 K10. Alan

copied and pasted from the mentioned link.........................

Here it goes:

To disable the auto headlights you need a 1.5K ohm resistor (Radio Shack) and 2 Scotchlok Tap Connectors (Walmart).

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). I don't remember if white is A4 and gray is A6 or vice versa. It doesn't matter anyway. BTW - there are two gray wires in the connector. The one you want is the one farthest away from the white wire.

Tap the gray wire from the plug (C3) to one end of the resistor and the white wire to the other end. You don't need to cut the wires. Make sure you tape up all wires to prevent a short. You should now have a gray wire coming from C3 tapped to one lead of the resistor and the white wire from C3 tapped to the other resistor lead *. Plug C3 back into the BCM. 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! Takes about 5 minutes.

*You can add a switch here if you want. Just connect one end of the resistor to one of the wires in the connector (doesn't matter which one) and the other end of the resistor to one side of the switch. Then connect a wire from the other side of the switch to the other wire in the connector. This will allow you to turn Twilight Mode on and off.

Ummm, dude, why would you add a second switch , when the factory DOME over ride switch does exactly the same thing??? Sure you need to push it four times , rather than throw a rocker switch one way, but i mean, isn;t adding a switch kind of redundent? The point of having the factory option to turn it off on occasion is the exact same thing you are doing adding a switch and resistor in series.