got some led tail lights a couple years back and I noticed that my cruise control stopped working due to them and I remember I did not install any resistor with my led tail lights. I did some research and seems like i need to install a inline resistor to get the cruise control to start working again but there was no consensus value on what specs the resistor needs to have. anyone with tips or a work around for this?

thx

 

The resistor value is something worth resolving, however the braking circuit is not straight forward.

Essentially the issue is that unlike a filament bulbs with an "Off" restance of around 5ohms or so, LEDs are "High" resistance. Thus the montoring module interprets the high resistance (which probably floats to 12V) as "Brakes-On" and so disables the cruise control.

I suspect its a "shunt" resistor rather than an "in-line" one, and the problem with that is the power dissapation when braking, 27 watts the power of a small soldering iron (per bulb !)

So the question is what is the highest value resistor that can work reliably, something around 330R would be good but I've never tried it.

So I've just come across this article which explains it better and may help. Their solution is to fit a 215R resistor between the brake-pedal switch (White Wire I think for Hummers) and ground to simulate the load, I'd be tempted to use a power resistor type (see here) and bolt it to the chassis so there is less fire risk!

It's a lot of effort and risk.

Keep us posted!

 

What type of lights are they? The ones I have came with a small black box with their own connector on each light which plugs in. I am assuming it is the resistor for each light because without them plugged in the lights do not function correctly. My lights also blink opposite of the lower bumper lights when the flashers are on. However, they blink in unison with the emergency flashers. I have tried to decipher the wiring to determine why in the hell that happens but I have never gotten to the bottom of it.

In your case, I would determine which lights you have and if they have the plug for the manufacturer resistor box and I would reach out to that manufacturer to get a hold of those boxes.

 

LoJac963Think hnijhar is talking specifically about LED brake lights with the known cruise-control issues associated with them.



My flashers work "opposite" just like yours (standard bulbs fitted) even with the harazard emergency button pressed, however my truck has been modified for UK roads which require Ambar rear indicators so this may be related.



Looking at the wiring diagrams, and if I'm reading them correctly, both the front and rear turn indicators have "dual-filament" bulbs (though I've never seen one physically) However, the rear shows only one filament used, whereas the front have both filaments wired but to different circuits.




So if your lamps are only "single" perhaps they are on the opposite "phase" which may explain the difference? (see attached)



All guess-work on my side..

 

thanks for the replies! was thinking of getting a 50w 6ohm resistor and attaching to each brake light in the rear in hopes of correcting the problem.
anyone have experience with this?

 

That's interesting. If I remember correctly, if I place a regular halogen bulb in the lower bump light the two will blink in unison but when I add LEDs to the bottom bumper lights in combo with my full LED tails they blink opposite. Thanks for the diagram, might be more useful than trying pins with a multi meter and test light over and over again.

 

Done! Cruise control is fixed!

Bought 50w 6ohm resistors on amazon because they were easily found on amazon and have heard of other people using the same on other gm vehicles. Popped off the rear passenger tail light, drilled the resistor into the metal to help cool it down, tapped the resistor into the red major wire and then the other end of the resistoe into the green black ground wire.
It apparently Shoukd work by only doing rear passenger but I went ahead and did rear driver too bevause I was too lazy to test drive:

to test if the wiring is connected properly it’s better a good idea to step on brake for 30 seconds and feel the resistor and if it’s warming you know that the wires are connected enough to make the resistor work, if they stay cold you have a bad connection or resistorn