Disable Headlight Twilight Feature (Auto On)

[99GoldSilverado]

I have read several posts asking for information on how to disable the twilight (auto on) feature on the headlights of 99 FSCs.
I wanted to do this myself so I searched and found several methods of doing it.
This is the easiest. You don't have to take the dash apart or cut any wires. Just a simple in line resistor.
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.

[JB]

nice tech article

I did this to mine and alot of friends a year ago and it works great, I used a switch.

http://www.fullsizechevy.com/forum/s...t&pagenumber=2

[nikon]

SWEET!! thanks alot...I really hate those auto headlights....I had to take my whole dash apart to do so on my camaro, this is alot easier

[tracetrimble]

i did this mod to my 99 a while back. i used a 1.5k ohm resistor, and mounted a maintained pushbutton switch next to the airbag disable switch. it worked great for about 3 weeks, and then quit working at all. the headlights are back to the way they were, as if the switch was not there. i checked the resistance, and i'm still getting 0 and 1.5k ohms at the blade connectors. i used those little snap type wire taps on the factory wires, which i've never really had a problem with in other applications.

has this happened to anyone else? i'm thinking possibly the PCM thinks i've moved to Alaska or something, and compensated for the extra resistance? only problem w/ that is i've left the switch off for a month or so, and it didn't correct itself. did i fry something, or possibly just lose connection somewhere else downstream?

TIA ~Trace

[castrol]

Uh, can't you guys just push the 'dome over-ride' switch 3 times and disable it that way?

Works on mine.

[tracetrimble]

that doesn't work on '99 models.

[castrol]

Really? I thought it worked on all of them. Oh well... just wondering.

Kills the DRL's too.

[tracetrimble]

Anyone know where the DRL module is on a 99 Silverado?

I did this mod on my Camaro, and it works perfectly: http://www.xse.com/leres/ss/drl.html

I think the pin you ground out is used for a DRL override button on the police packages.

[chaz2009]

Is it possible for a dealer to turn this off with their scan tool ?

[savage420]

Hey does this first post work on a 02 ?

Also ive tried the push the 'dome over-ride' switch 3 times and disable it that way trick and i dont work ether .

[savage420]

Anyone?

[JB]

Originally Posted by savage420

Hey does this first post work on a 02 ?

Also ive tried the push the 'dome over-ride' switch 3 times and disable it that way trick and i dont work ether .

Yes it will work fine

[savage420]

Originally Posted by JB

Yes it will work fine

Yeah the push the button crap to disable dont work on all 4 of our GM trucks in our family....i seriously dont think it works on ANY of them as it dont on 3 of my friends rigs also...no biggie though!!!

[juicedwagon]

i did this on my 02 silverado and it didnt seem to work, are the 02 chevys different?

[Nick]

Originally Posted by savage420

Yeah the push the button crap to disable dont work on all 4 of our GM trucks in our family....i seriously dont think it works on ANY of them as it dont on 3 of my friends rigs also...no biggie though!!!

Because you live in Canada.

[savage420]

Originally Posted by Nick

Because you live in Canada.

Whats the diff

Anyway i already modified mine with a switch to work with my H.I.D's

[Nick]

Originally Posted by savage420

Whats the diff

Anyway i already modified mine with a switch to work with my H.I.D's

Aren't you guys required to run DRL's?

[savage420]

Originally Posted by Nick

Aren't you guys required to run DRL's?

Who knows? LOL Nobody says anything to me so im not to worried about it

[Gerald]

This is how to dissable them on the 03+.......
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This mod will allow full control over your lighting using the manual switch on the dash.


This is copied from Diesel Place,

The wires for the Light Sensor go to the TBC. The "J" connector numbers are molded into the TBC 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 TBC end and not the ones going to the sensor.

No More Auto Headlights!


He used a little blue wire for the jumper. I found that leaving them pluged into the BCM, and using a small paper clip is alot easier.

Basics are...

Find the J3 plug, then the A4 (white) wire, jump a paper clip from this wire, over to the J4 plug, to the B7(black) wire.

I used heat shrink tubing over the paper clip to only expose 1/2" on both ends so its not to short out on anything.

Hope this will help you guys too!

[Z71Truckin]

Sorry but i dont get what this does. Does it keep your lights off 24/7. Or what does it do?