How To: Disable Auto Headlights on 03-07c Trucks


Bed Dent Club Founder
Mar 24, 2012
Albany, NY
As the title states, this is going to show you how to disable your auto headlights.

You may be wondering, "Why would someone would want to do that?" It is a useful mod for those running HID lighting in their low beams. What this will do, is keep your HID ballast from starving from lack of voltage while the truck is starting, since the lights turn on as soon as the key is turned "ON" (if dark).

This mod will allow full control over your lighting using the manual switch on the dash.

The wires for the Light Sensor go to the BCM. You need to access the BCM connectors in order to perform the mod. Here's a brief walk through of how to get to the BCM:

Remove the dash bezel

Remove the lower kick panel. It is held in with two 7mm screws, one on the lower left by the parking break release and one on the lower right.

After doing so, you'll see something like this:


Each connector is lettered and numbered. The "J" connector numbers are molded into the BCM under each connector. The "A/B" are molded on the ends of the connectors and just count wires to get to the right terminal.

Connector J3 terminal A4 = white wire for sensor


Connector J4 terminal B7 = black wire for sensor return


If you have auto climate control the black wire is shared with the left and right solar controls.

You could jump a small piece of wire between J3-A4 (white) and J4-B7 (black) to disable the Light Sensor.

If you have manual climate controls the black wire only goes to the Light Sensor so you could cut J3-A4 (white) and J4-B7 (black) and connect them together. Just be sure to connect the wire on the BCM end and not the ones going to the sensor.

What I ended up doing to avoid cutting and soldering was locating the J3 plug, then the A4 (white) wire, jumped a paper clip from this wire, over to the J4 plug, to the B7(black) wire. I used one of the colored paperclips so it wasn't exposed to other metals, potentially causing a short. Any type of wire that is protected/wrapped will do.


And that's it. All in all it took 5 minutes to do this. Very useful and I am glad I have full control over my lights now via the headlight switch.
Yup you could do that too. Also, Tony (B005TED) just installed the Jatronix (sp) delay relay, which is voltage sensitive. It only send power to the ballasts after it receives the full 14ish volts when the truck is on.

This is just the cheapest and quickest way to do it, that's all.
Different for 99-02 because of different bcm. Mine looks completely different from yours the connections and numbers are different

Sent from my potato
But I found the connections I need, but gmfs how to's are saying I need a resistor. I wonder if I could just jump them like you did and it would act the same
Update you need to find the purple c3 block on the 99-02 BCM and find the A4 and A6 wires and run a resistor between them. Mod doesn't work without a resistor for 99-02 at least