jackyshaikh

This may help if someone wants todisable DRL Option


Document ID: 2022756
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[/align]#PIT4328A: DRL Disable Procedure - keywords daytime disable headlights headlamps lamp light - (Oct 2, 2007) [/align]
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Subject:
DRL Disable Procedure[/align][align=left]



Models:
2007-2008 Cadillac Escalade, Escalade ESV & EXT[/align][align=left]




2007-2008 Chevrolet Avalanche, Tahoe, Silverado, Suburban[/align][align=left]




2007-2008 GMC Yukon, Yukon XL, Denali, Denali XL, Sierra[/align]

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This PI was superseded to update model years and Recommendation/Instructions. Please discard PIT4328.
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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 1-800 828-6860.
**** 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.




GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.



WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION [/align]© 2008 General Motors Corporation. All rights reserved. [/align][/align]Please ignore or delete the post if someone has already posted.

Beardookie

THANK YOU for posting that bulletin. It shed light on a couple of matters.

My experience from working on my 2008 Silverado:

DRL's - Just pull DRL and DRL2 fuse from fuse box under the hood and no more Daytime Running Lamps. No reprogramming needed.

AUTO HEADLIGHTS - Couldn't quite figure this one out, so if ANYONE has a fix, let me know. This is what I know about it though:

Photo-transistor (aka "ambient Light Sensor", which I will refer to as ALS) conducts the supply voltage when daylight hits it. Installing the 600 ohm resistor tricks the computer into thinking it's always daylight. Installing this resistor leaves your instrument panel blinding bright at night time. So short of installing a manual switch to switch between daytime and night time, you're kinda screwing yourself by installing this resistor (I removed mine after the first night).

One terminal for the ALS is the supply voltage, one goes to ground. If you remove the ALS, your lights will be on all the time. If you install the resistor, your lights will always be off (unless you manually turn them on) and your instument panel will be bright.

If you could find a "ground" when your headlights aren't manually on at night, but "open" when your headlights are manually on, you're golden. Just wire the resistor between the positive voltage and whatever circuit that does that magic number. No the DRL circuit doesn't work as it is driven by the ALS circuit. Couldn't seem to find a 12VDC "not gate" to wire between pin 1 of the headlight switch and the 600 ohm resistor.

Pin 4 on your headlight switch seems like it should be the "auto" switch position on the headlight switch. This pin isn't connected to anything, so it's not automatically grounded when in "auto" position. There's no lead or run on the printed circuit board inside the switch for this switch setting. Otherwise you'd be able to ground the pin there and you'd be golden. Additionally, the "off" signal appears to be a togle signal as when I ground the other end of the resistor to that circuit, the headlights would only be on every-other time I started the truck at night.

Thought about installing relay using the white wire (pin 1) which goes to ground when you turn your headlights on to energize a relay which will switch the 600 ohm modified ALS circuit from day mode to night mode. Then when you turn your headlights on at night, the instrument panel will dim with the rest of the dash. I bought a relay, wired it 1/2 way up, and then I read something about "protection diode" for relays to keep high voltage spikes from hitting your solid state computer and got lost in the technical BS. I was trained to fix electronics, not to engineer them, so I gave up on that idea before I had an opportunity to fry the Body Control Module (BCM). Apparently this happens at both the "coil" side of the relay and the "switch" side, so wiring it to another circuit (forget which one, but in the engine compartment) wasn't an option either.

I concluded that since I turn my headlights on during the day anyway (well, 99% of the time), the auto-headlight feature is only slightly annoying when driving through the forest ('cuz those don't exist in WA State) or a tunnel. If I want to check the time or the radio station, it's really not that urgent of a thing and I can wait to get that information. However, not having DRL's has to save some light bulbs, right?

SabrToothSqrl

the amount of power your DRLs consume is very small compared to the lifesaving feature that they are...

your may get 0.0001 more MPG from your vehicle, but I'll leave them on. Infact, they are required to be on the vehicle by law, and here in PA i'm not sure it would pass inspection without them...

Canada has required them since '98 i believe.

of course, that's my experience. they make cars easier to see...


Numerous studies done worldwide since the 1970s have tended to conclude that daytime running lights improve safety.[1][2][3] A 2008 study by the U.S. National Highway Traffic Safety Administration analysed the effect of DRLs on frontal and side-on crashes between two vehicles and on vehicle collisions with pedestrians, cyclists, and motorcyclists. The analysis determined that DRLs offer no statistically-significant reduction in the frequency or severity of the collisions studied, except for a reduction in light trucks' and vans' involvement in two-vehicle crashes by a statistically-significant 5.7%.[4]

Daytime running lamp - Wikipedia, the free encyclopedia

ousig2408

I dont see why a civilian would want to disable the DRL. on the other hand I really wish we had the option to manually turn the lights on or off and not just AUTO or on. because there is no reason for the HID lights to fire up when we start the truck in the garage during the day or other times when they will turn right off once you get moving. I know you can hold the dial to off when starting but that also turns off the DRL and a pain to do everytime.
Many cars have off, AUTO, ON for the lights so you can manually work the lights.

73shark

If you turn the control CCW and release, it turns off the DRLs and auto headlite feature 'til next restart.

Beardookie

If you want to hear about why I disable my DRL and am researching disabling auto-headlamps, read on. I’m posting this because I’ve seen too many “Why would you do that?” posts on other forum sites and this one (although not necessarily this post). So this is my *attempt* to explain for those that actually want to know.
Please skip this post if you could care less, it’s pretty long!
* * * * *
(FYI, I posted to this subject referring to my Silverado, which is similar to the Tahoe model, and when the Tahoe line initially came out, were basically the same thing as the c/k series but with different bodies. They are more different now than they were then, but many similarities still exist.)
Don’t get me wrong, I’m not trying to start a debate on DRL/Auto-headlights, nor am I arguing the benefits of having your headlights on during the day. Motorcycles are mandated to have this feature for safety since the 70’s (and I have my high-beams on during the day on my bike if I’m going further than 10 miles). Believe me or not, I actually turn my actual headlights on every time I start one of my vehicles, and so does my wife. We may go through more headlamps doing so than your average person, and cars still like to pull out in front of us because of the ohmygoshIcan’tbebehindthistruck mentality, which is where I'm guessing a lot of accidents happen. In the Seattle area, where it rains a good portion of the year and most people living here aren’t from here, a dark colored car without its lights on blends in all too well with the dark colored road. We have the” lights on when it’s raining” law, but it’s enforced about as much as the “keep right except to pass” law. Having your lights on is also beneficial on the eastern side of my state where it’s high plains desert and drivers tend to zone out.
I don’t disable DRL for fuel savings. If I was that concerned, I’d have a Volt or Prius or some other electric car. Even though DRL's might be low current, a relay can induce a high voltage/low current into the circuit if wired into a computer's logic circuits. High voltage can exist with low current as evident with seeing a spark when touching a doorknob = 3000 volts for tribuletric effect (or whatever it's called) which is very low current. More than enough to fry a solid state device such as a vehicle's computer.
DRL's may or may not be required to be standard equipment by federal law, but who cares as that requirement is satisfied when the truck is built and ends the minute it gets registered in my name. I disable DRL because there are times when I don’t want my lights on. I’m not a civilian, so driving through checkpoints requires headlights to be dimmed so you don’t ****-off the guard who you just blinded. Not too much of an issue with my ’08. However when GM first came out with DRL as standard on the ’96 Sierra/Silverado, they didn’t include a feature to turn it off, so my ’96 and ’97 both have the fuses removed. When I lived in VA, I’d install the fuses for their yearly safety check.
The ’08 Silverado, which is my 5<SUP>th</SUP> wheel tow vehicle, having the headlights turn on every time I turn on the ignition at a campground at night is very rude when you light up a tent or another RV when it’s dark (more of an auto-on feature than DRL, but they’re linked together on the ’08). True, I can hold the headlight switch in the “off” position when I turn the ignition to “on”, but it’d be easier if the feature was just disabled. More importantly, if I’m driving through a forest/tunnel/rounding the back side of a mountain, the auto-headlights think it’s night and turn on (which normally I wouldn’t care since my headlights are already manually on) but the whole instrument panel dims and is now not readable when sunlight hits. Now I can’t keep an eye on transmission temperature/tire pressure, or what gear is manually selected when going down a mountain pass until the sensor thinks its daylight AND the computer “polls” the sensor while it’s registering as daylight (shade from trees aren’t a constant, it’s shady, sunny, shady, sunny, shady…) which can take as long as 59 seconds AFTER you reach a spot of decent time of sunlight as the computer polls the circuit every 30 seconds.
Personally, I think DRL and auto-headlights is a great feature for 85-90% of the population, particularly those who aren’t smart enough to turn on their headlights on. However it is not for me, regardless of what someone or some gov’t agency thinks. I work for Uncle Sam, but the hair on the back of my neck stands up every time they do something because it’s in the interest of my safety.
While we’re on the subject of disabling mandatory safety features, my next project I have is to build a non-metalic pressure tank to strap to the underside of my ’08 with at least one tire pressure monitoring (TPM) sensor in it to fool the computer. It appears one of my TPM sensors died and causes the annoying “Hey dummy, you have a flat” on the dashboard and I’m not about to spend $80-100 to have that fixed when I usually check the tires the old fashioned way frequently (habit that crosses over from my motorcycling hobby) and plan on replacing that tire next year as it is wearing down. This is a good example of how someone’s mandatory-because-it’s-best-for-you is screwed up. Also, If I’m hauling 11,000 pounds, with about 3,000 pounds of pressure over the rear axle from the king-pin (which is within the tow/haul specs of the vehicle), the tires are going to heat up. They should be pressurized to 80PSI cold for this. However, while driving a few hundred miles, the TPMS starts telling me that my tire pressure is too high because the tires are at 94PSI and I loose the ability to view tranny temp or other information. SO, instead I air down my tires which causes more heat and actually increases the chance of tire failure just so my information display works. How “good for me” is that?
Okay, now I started rambling, but there’s a few valid reasons why someone would have use for disabling DRL/auto-headlights. Other’s might do it because they think it’s “un-cool” to have their headlights on, but that’s them doing them. This is me doing me, and I'm shutting up now.

LTL4life

I most definitly have to agree with you. On my vehicles that didnt have auto lights or DRL's , i always turn on the headlights day or nite. The quality of drivers on the road today is horrible! anything you can do to get their attention is a plus.

SabrToothSqrl

in PA and FL (and maybe others) you MUST turn your headlights on when operating your wipers... (ie it's raining)...

so many time's it's so hard to see grey / dark cars in pouring rain, even in daylight.... I wonder if I hit them without lights on (them) if it's there fault I couldn't see them... or if a % of the accident would be their fault...?

73shark

Not sure when they added it but on the 2010s, the headlites come on after about eight wiper strokes.

beardookie: Lot of good reasons. My reason is I always felt it detracts from motorcycles who have their headlite on to be seen when everybody on the road has 'em on. They no longer stand out. Maybe they'll need to put a pennant on a pole like I did on my son's Big Wheel.

nj85z28

I'll make this a sticky. Thank you for your article