How to disable the auto headlight system on 1999-2002 GMT800's

[daddy]

The following is a step-by-step guide to disabling the auto headlights on any 1999-2002(Includes Silverado, Suburban, Tahoe, Sierra, Yukon, Yukon XL, Denali, Denali XL). I can verify it will work on 2001's and 2002's for certain. It should also work on the '99's and 2000's if equipped.

For this mod you will need one 1.5kOhm 1/2 watt resistor and some way to connect it to your pre-existing wiring on your BCM.

HOW TO:

1. Locate the BCM (Body Control Module) under your dash.
2. Disconnect the Purple connector (C3) from your BCM.
3. Locate the white wire (A6) and the gray wire (A4).
4. Cut both wires and splice in the the resistor.
5. Tape or heat shrink everything to mitigate the chance for shorts.
6. Reconnect the C3 connector back to the BCM.

Done. No more AHL's.

​

 

[ScottyBoy]

Nice write up!

 

[ScottyBoy]

And just so I'm clear, you "cut" the wires and connect the two wires together with this resistor on the BCM end of the wires (leaving two uncut ends hanging disconnected)?
Or do you actually end up with both wires the same way they were stock, but with a resistor connecting the two of them?

 

[Alljackedup408]

i might just do this mod. mine are aggrivating cause mines a 99.. and i cant over ride them.. when im sittin in a drive thru or sumtin.. my lights are all up in peoples windows.. and im not tryin to be a dick so .. i shut my truck off... push the parking brake in 1 click, then start it and turn the parking lights on.

 

[Alljackedup408]

is there any way i can stick an 01 or 02 switch in my truck? i rather do that then be cutting wires on the BCM.

 

[daddy]

is there any way i can stick an 01 or 02 switch in my truck? i rather do that then be cutting wires on the BCM.

You can also just tap into the wires without cutting them, I just chose to cut them. If you don't cut them, you can always just cut the lead to the resistor later to enable them again.

 

[Alljackedup408]

is there any way i can stick an 01 or 02 switch in my truck? i rather do that then be cutting wires on the BCM.

You can also just tap into the wires without cutting them, I just chose to cut them. If you don't cut them, you can always just cut the lead to the resistor later to enable them again.

yeah.,, i might just do that. just working at the dealer ship ive fixed a bunch of vehicles were people have tried modding stuff or rewiring around things... it just makes a rats nest. so im very shy when it comes to dealing with module wiring.

 

[daddy]

is there any way i can stick an 01 or 02 switch in my truck? i rather do that then be cutting wires on the BCM.

You can also just tap into the wires without cutting them, I just chose to cut them. If you don't cut them, you can always just cut the lead to the resistor later to enable them again.

yeah.,, i might just do that. just working at the dealer ship ive fixed a bunch of vehicles were people have tried modding stuff or rewiring around things... it just makes a rats nest. so im very shy when it comes to dealing with module wiring.

The resistor is tiny and the wires are so close together, you shouldn't interfere with anything at all.

 

[ScottyBoy]

is there any way i can stick an 01 or 02 switch in my truck? i rather do that then be cutting wires on the BCM.

You should be able to wire it up but with a switch so you can bypass them only when you want to. Just a thought..

 

[ScottyBoy]

Daddy? Will the DRL's stay on if you bypass them this way? My Father in law saya he may want this on his 99, but his motive is to go stealth. So at night, will the DRL's still be on if you leave the headlights off? If so, I'll need to find a way to bypass those as well. If I really need to, I guess I could wire a relay to interrupt the power going to them.