ericnottelin

Found this and wondered if anyone had something similar for the new body style truck (mine is an 08).

Thanks

Eric


FOR '99-'02 TRUCKS ONLY w/o AUTO CLIMATE CONTROLS

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). I don't remember if white is A4 and gray is A6 or vice versa. 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!

ericnottelin

Also found this.

<table border="0"><tbody><tr><td valign="top" width="100">Subject:</td><td valign="top">DRL Disable Procedure - keywords daytime disable headlights headlamps lamp light #PIT4328A - (10/02/2007)</td></tr></tbody></table>
<table border="0"><tbody><tr><td valign="top" width="100">Models:</td><td valign="top">2007-2008 Cadillac Escalade, Escalade ESV & EXT</td></tr></tbody></table><table border="0"><tbody><tr><td valign="top">2007-2008 Avalance, Tahoe, Silverado, Suburban</td></tr></tbody></table>2007-2008 GMC Yukon, Yukon XL, Denali, Denali XL, Sierra

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:

**** THIS INFORMATION APPLIES TO U.S. VEHICLES ONLY ****

All requests for Daytime Running Lamps (DRL) disable are to be referred to Techline Customer Support Center (TCSC). Instruction about vehicle qualifications and requirements for DRL disable will be provided by TCSC. TCSC is GM's central record keeping location for all of these requests. TCSC toll free number is X-XXX XXX-XXXX.
**** THIS INFORMATION APPLIES TO U.S. VEHICLES ONLY ****

Requests for DRL/auto headlamp disconnects must be made by appropriate agencies. The vehicle in question must be owned by a law enforcement agency, military agency or security company. (City/State, Sheriff, FBI, CIA, DEA, Emergency Vehicles.Etc.) It is recommended the dealership obtain a letter on the agencies letterhead requesting the DRLS/auto headlamps be disabled. The letter should contain the specific vehicle identification number which will be disabled, and a statement which reads, "the DRL/auto headlamp system will be made fully operational prior to disposal/sale of the vehicle." the letter should be kept in the vehicle service file at the dealership.
Recommendation/Instructions:

Procedures to disable daytime running lamps (DRL):

Have the dealership technician call Techline at 1-800-828-6860 and request a new calibration for the truck body control module (tbcm) that will disable the DRL's. Recalibrate the TBCM with the new calibration.

Procedures to disable to auto headlamps:

Unplug the ambient light sensor and put a 600 ohm resistor in place of the sensor. The resistor will command the TBCM to turn the auto headlamps off. The headlights will now have to be manually turned on with the headlight switch.
Secure the resistor and connector to prevent rattles.etc.
Note: Vehicles equipped with Automatic HVAC (RPO CJ2) may have a light sensor that also includes the sunload sensor for the HVAC system. Make sure the resistor is wired into the ambient light sensor signal wire (Circuit 278) and ground (Circuit 1851). This can be achieved by backing out pin 2 at the light sensor and removing the terminal and adding the resistor to the wire and then splicing the other end of the resistor to the ground wire 2 inches from the light sensor.
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

ericnottelin

I need the schematics for an 08 silverado bcm. Anyone have any ideas?

QUETRANPA

Eric I know this is an old question but did you find the answer already, or did you try putting a 1k resistor right at the light sensor harness like I suggested a while ago?
Anyway I do have those schematics, just let me find them a I will get back to you, I found them at a different forum, they are a total of 669 pages of the whole truck wiring system, I downloaded them but let me find them in that forum and post the link, just let me know if you still need them.

57 DeLuxe

I went to hardware store, bought a plastic cap, like for the end of a bare metal rod. I installed over the sensor. Drawback, as my lights were always on, the radio and control panel bulbs started burning out. The bulbs can not be replaced.

QUETRANPA

but what kind of truck do you have? I guess you wanted to have your lights always on and that is why you covered the light sensor with the plastic cap to make it think is always night time!
on the other hand as far as I know the light bulbs in the instrument panel can be replaced, actually some guys replace them with LED's, but I don't know what kind of truck you have.

ericnottelin

Quetranpa, No I have not found any permanent solution to this. I got a copy of the wiring diagram. It appears slightly different then the ones for the older systems. It looks like the sensor has one hot and one ground wire going to it. Thus, it appears the light sensor is actually GENERATING an electrical charge and sending it to the BCM. I didn't think adding the resister would help with this type of setup because it would only limit the charge the sensor was generating and would probably only set it to night time only. If it is a generating sensor, then I could run a hit wire from the fuse box, with a resister attached, and splice it into the bcm. But I would need better schematics with detailed wire descriptions.

I could be wrong as the schematic I got was very very vague. If you have the link or file for a more detailed schematic for our trucks, It might be more helpful.

Thanks

Eric

QUETRANPA

Hi Eric sorry for the late reply, here's what I found in another forum
http://www.c-hock.com/downloads/gmfs/08-electrical.pdf
I hope this helps
as for the resistor in the light sensor, it actually makes the sensor think is day time all the time, yes and at night you just turn your headlights on manually, this is to disable the automatic headlights, specially if you have HID's 'cause they flash when you start your truck, and that shortens the life of the ballasts, let me know if you have any questions.

ericnottelin

Thanks Quetranpa. I will look at it. I have to figure out if I can put the resister in line at the BCM so i don't have to take half my dash apart to get to the light sensor wires. Unless you happen to know an easy way to get the sensor out? Thanks again.

Eric

ericnottelin

Well, thanks to Quetranpa, I was able to look into this further. Unfortunately I'm screwed. and here is why.

- First, the ambient light sensor (the one for the head lamps) controls two (2) SEPARATE systems, the headlamps and the interior dash lights. To reiterate, these systems are separate from each other. Weird huh?

- So, I tore apart my dash and bought the resistor. Put it in line and voila, I have manual control over my headlamps. Problems is, the computer didn't turn the dash lights down so they are BRIGHT and I don't have control to dim them. So I can choose to have manual control over my head lamps and be blinded by my dash lamps or leave it the way it is. BUT THIS ISN'T THE BEST PART

- The reason I have been looking into this is that if it gets too cloudy outside or I go under an overpass, my dash lights dim because it thinks it's dark outside. Now I can't see my radio, etc.

- So back to the mod. Even if I figured out the exact way to allow me to control both the head lamps and dash lights (I believe a stronger resistor is needed) I have another problem. The dash lamps have two settings. A day time and a night time setting. If I bypass the ambient light sensor, I have to pick ONE. The bad thing is the night setting does not get as bright (even at the max setting) as the day setting. So, I have to pick either the day setting and get blinded at night or the night setting and I will not be able to see the dash during the day time.

- So this is one design flaw for Chevy that I don't see a way around. If anyone else discovers a different idea, I would be very interested in hearing it. As Quentranpa mentioned, I think the guys that have HID lights will run into this problem and be very interested in an answer.

Hope this helps

Eric