LED Brake Light Bulbs Will Disable Cruise Control on GMT800

[Scott in AZ]

Apparently everyone on the WorldWideInterWeb already knows this, but I can now confirm that LED brake lights will cause the Cruise Control to stop working on GMT800 SUVs. I replaced the left and right brake light (aka tail light or stopping light) bulbs in my 2001 Yukon, and the Cruise Control worked fine. Then I also replaced the top center brake light fixture above the lift gate with a Dorman LED fixture, and the Cruise Control stopped working. It would not set on the speed. Then I swapped the original 3157 incandescent bulbs back into left and right lower brake lights and Cruise Control works now fine again. I’m trying to noodle why this is; something about the amount of resistance in the circuit the Cruise Control monitors to turn off when brakes applied, but I can’t figure this out since the Cruise Control surely does not put current in the brake lamp circuit.

I decided against installing resistors. Why would you do that? A resistor converts electrical energy to thermal energy. The current and power increases and you lose the benefit of LED efficiency, just to make more heat.

So I’ll keep the the LED fixture on top center brake light and run with ole’ fashioned 3157 incandescent bulbs on the left and right brake lights, and the flashing turn-signal lights. I’m now running all LED interior (it’s awesome, easy upgrade) and LED on exterior head lights, daytime running lights, fog lights, center brake light, and reverse illumination lights. I retained incandescent bulbs for the amber turn signal lights (front and back) and red brake lights; replaced bulbs with new but not LED. I also polished the headlight enclosure with a Meguiar’s kit, and replaced the brake light enclosures with Dorman aftermarket enclosures. The whole project was probably $250, mostly for the new rear fixtures and fig lights, but it’s a nice refresh on a 23-year old vehicle.

 

[Marky Dissod]

Don't mind using ol' fashion incandescents for nearly every other bulb ...
But I want headlights, , fog lights, reverse lights, and brake lights too bright to be directly stared into without discomfort / disorientation - ought to encourage people to keep a safe distance from my vehicle.

I'll figure out how to reenable the cruise control later. If a few resistors are necessary, ok, so be it.

 

[Scott in AZ]

You should really give the interior lights a try, Marky. It’s amazing how much more light. This is the courtesy lamp in the rear door.

 

[Marky Dissod]

Interior already has LED lights - yes they are MUCH brighter, and usefully so.
Still not sure about headlights; LED vs HID ...
Fog lights backup lights and brake lights will be painfully BRIGHT LEDs, soon as I find painfully bright ones ...

 

[Scott in AZ]

Painfully bright …. I think there’s a Seinfeld episode on that.

The reason I kept the top center brake light LED fixture and swapped back to incandescent lower left and right is because I could tell the difference on the top center LED vs incandescent, but not the lowers. I don’t think there’s an advantage to LED lowers. Same light, same current draw once you add the resistors. But not worth trading for Cruise Control without resistors. Is what I think. But You do you, bro’. See you out there!

 

[04TahBro]

I found that if you have a 7 pin trailer plug you can plug in a 7 to 4 pin adapter with little LEDs on it and that will be enough resistance to get your cruise to work again. Ill post what I bought to get mine back on.

Robot or human?

 

[S33k3r]

Apparently everyone on the WorldWideInterWeb already knows this, but I can now confirm that LED brake lights will cause the Cruise Control to stop working on GMT800 SUVs. I replaced the left and right brake light (aka tail light or stopping light) bulbs in my 2001 Yukon, and the Cruise Control worked fine. Then I also replaced the top center brake light fixture above the lift gate with a Dorman LED fixture, and the Cruise Control stopped working. It would not set on the speed. Then I swapped the original 3157 incandescent bulbs back into left and right lower brake lights and Cruise Control works now fine again. I’m trying to noodle why this is; something about the amount of resistance in the circuit the Cruise Control monitors to turn off when brakes applied, but I can’t figure this out since the Cruise Control surely does not put current in the brake lamp circuit.

I decided against installing resistors. Why would you do that? A resistor converts electrical energy to thermal energy. The current and power increases and you lose the benefit of LED efficiency, just to make more heat.

So I’ll keep the the LED fixture on top center brake light and run with ole’ fashioned 3157 incandescent bulbs on the left and right brake lights, and the flashing turn-signal lights. I’m now running all LED interior (it’s awesome, easy upgrade) and LED on exterior head lights, daytime running lights, fog lights, center brake light, and reverse illumination lights. I retained incandescent bulbs for the amber turn signal lights (front and back) and red brake lights; replaced bulbs with new but not LED. I also polished the headlight enclosure with a Meguiar’s kit, and replaced the brake light enclosures with Dorman aftermarket enclosures. The whole project was probably $250, mostly for the new rear fixtures and fig lights, but it’s a nice refresh on a 23-year old vehicle.

Sorry I'm late to the party, but have you tried any of these solutions?

1) Novita LM487 Flasher
2) LEDs with built in resistors

 

[Logan5]

So I been running "painfully bright" LEDs on all my exterior lamps, headlights, brights, fogs, DRLs, brakes, turns, reverse, etc. The interior bulbs have been replaced with LEDs as well, but not bright whites, inside I went for 'Pimp Purple'.

Anyways, I been running this setup for over a year now and my CC was working fine until yesterday. Suddenly it won't set or come on at all. Banging my head against the wall trying to figure out what changed when it hit me. I had a trailer hitch ball in my receiver, because I was towing a trailer, but I didn't have the trailer hooked up. When I don't have the ball mount in the receiver I had a 4th brake light hooked up to the trailer wiring plug.

So, as you can guess, without the added resistance of the 4th brake light on the trailer harness, my LED brakes weren't enough resistance and my CC stopped working.

I might get what 04TahBro suggested so it's on all the time.

 

[Tahoe Yukon Guy]

I had the same problem. Saw a YouTube video and bought Sylvania 3157 SilverStar Incandescent Mini Bulb (Pack of 2) - 3157STBP and it solved the problem. this is a very bright white hybrid gas bulb that is as bright as the Sylvania LED's I put in it. Half the price of the LED bulbs.

​

 

[Doubeleive]

it should probably be noted that "some" led's will cause this, not ALL. I have ran LED's in 00, 03, 04, 05 and never had any issue with cruise not working
and if it does happen a simple $5-10 set of resistors will fix the issue or even maybe just 1 resistor.

 

[Rocket Man]

Lol the resistor just gets the circuit within the minimum needed to fool the system, you’re still saving a picowatt of energy over a months time. I mean, that’s why I run leds in my vehicles. I hate it when my truck sends me a big bill for electricity. Same with the gas bill.

 

[adventurenali92]

. I’m trying to noodle why this is; something about the amount of resistance in the circuit the Cruise Control monitors to turn off when brakes applied, but I can’t figure this out since the Cruise Control surely does not put current in the brake lamp circuit.

Someone more knowledgeable, correct me if I’m wrong, but As I understand it cruise control not working with LED bulbs in the brake lights is GM’s built in safety feature at work. It doesn’t have anything to do with cruise control adding resistance to the brake lamps circuit. If the system detects not enough voltage or resistance going to the brake lights, it assumes one or more brake light bulbs is blown, and then disables cruise control, as a safety measure. which I also don’t understand the logic in that either. Like ok “my brake lights are out, how is disabling cruise control going to make that scenario safer?!” But what do I know… lol.

 

[adventurenali92]

Lol the resistor just gets the circuit within the minimum needed to fool the system, you’re still saving a picowatt of energy over a months time. I mean, that’s why I run leds in my vehicles. I hate it when my truck sends me a big bill for electricity. Same with the gas bill.

Laughing cuz That’s where my brain went as well when I read the bit about losing the LED efficiency when adding resistors….. I’m really worried about the electrical efficiency in my big gas guzzling SUV….

 

[Burban22]

What is the part number or link to replacement rubber washers that go in the rear turn, reverse, brake bulb sockets?

My driver side taillight has all 3 but passenger side missing so the bulbs are loose in the plastic taillight housing along with dust and water able to enter.

 

[Rocket Man]

What is the part number or link to replacement rubber washers that go in the rear turn, reverse, brake bulb sockets?

My driver side taillight has all 3 but passenger side missing so the bulbs are loose in the plastic taillight housing along with dust and water able to enter.

That’s a generic part available at your local auto parts store. They should have a rack with little parts like that, Dorman usually has racks with what they call “FixIt” parts. Take one of the ones you have with you to match up but bulbs are all the same size from car manufacturer to car manufacturer, so there’s no GM ones versus Fird ones, they’re like rubbers everybody uses the same ones.

 

[DmitryGMT800]

Lol the resistor just gets the circuit within the minimum needed to fool the system, you’re still saving a picowatt of energy over a months time. I mean, that’s why I run leds in my vehicles. I hate it when my truck sends me a big bill for electricity. Same with the gas bill.

Switching to LEDs in brake lights would bring more safety as LED response is a bit faster than ordinary bulbs. Which in turn grants some time for driver to react. It can be seen how a vehicle ahead of me has a delay between the brake lights and the third brake light which is LED. Of course I would not not expect energy savings from this type of things LED is somewhat brighter as well - though it may depend on the specific model. By the way - I just wanted to share my issue with the LED in brake lights - right brake light led bulb is on all the time - but it has 2 volts and is very dim if compared to normal mode and braking mode... Does anybody witnessed this?

 

[S33k3r]

Trace the wire. That sounds like a bad wire, barely carrying current.

 

[Rocket Man]

Switching to LEDs in brake lights would bring more safety as LED response is a bit faster than ordinary bulbs. Which in turn grants some time for driver to react. It can be seen how a vehicle ahead of me has a delay between the brake lights and the third brake light which is LED. Of course I would not not expect energy savings from this type of things LED is somewhat brighter as well - though it may depend on the specific model. By the way - I just wanted to share my issue with the LED in brake lights - right brake light led bulb is on all the time - but it has 2 volts and is very dim if compared to normal mode and braking mode... Does anybody witnessed this?

Try a different brand also. Some cheap or even not so cheap ones wont work while others will for some reason. They all have little circuit boards inside.