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.

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[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.