Thread: LED lights and cruise control quit.

I have been adding LEDs all over in my car and lost cruise control functionality. I understand it is because the LED is a diode and either doesn't complete the circuit or show enough voltage drop. I am looking for any neat solutions without going back to incandescent bulbs.

I started out with cheap led projectors on the tail brake bulb and third brake light but the third brake light lit up on its own with lights on. Then I tried some can bus led brake tail bulbs and they did not light up the third on their own. I bought some ebay load resistors but they were so cheap and didn't work.

Please tell me what the LED's have to do with cruise control functionality? You could run no lights, ie no resistance, and your cruise would work.

It's definitely a thing. I'm not sure what the science behind it is, but I do know that LED's in the 3rd brake light causes cruise control problems. I've come across that multiple times reading threads on this forum.

Originally Posted by CHI2000GTP

LED's in the 3rd brake light causes cruise control problems.

^ This, yes. Headlights, no.

Also found that the otherwise normal sounding radio stations go static when I hit the brakes. I drive a lot in rural areas where few radio stations reach. I tried cheap LEDs from ebay as well as nice canbus super bright leds. The third brake lights are sylvanias and brakes/tails are can bus super bright leds for which I have always had excellent quality and zero trouble.

Hid headlights cause static on weak radio stations too. I tried ferrite coils on the ballasts but it didnt work. Figured I would live with it.

So should I try can bus third brakelights?

I had some LED headlights that caused interference. They were a plastic housing. When I replaced them with aluminum housing bulbs the interference disappeared.

The ballast isn't what causes interference on HIDs, its the light itself on ones that cause issues. The ferrite core needs to be placed close to the bulb. When I still had the plastic housing LEDs I placed some ferrite cores on the wire near the bulb, and while it didn't eliminate the interference it greatly reduced it.

And FWIW I had a HID high beam in my car at one point and it caused no interference issue. The only reason I took it out was the bulb length caused the beam not to project properly, so I just am dealing with halogen high beam bulb for now.

So if I want to keep LEDs in the third light then resistors will fix it? I will try swapping the third back to standard bulbs and see if it works. I hate to go backwards on the tails because they are brighter with the LEDs which the 97-03s need more brightness in my opinion.

I would try a resistor first. What can it hurt?

I have Diode Dynamics LEDs all around.

The flasher module solves the hyper flash issue but you also need to put load resistors on the front corners for the 3rd brake lights and cruise control to work together.




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Ok why the front corners? I have a new flasher so no more hyper flash.

Originally Posted by green97

I will try swapping the third back to standard bulbs and see if it works.

I would do this. If your cruise starts working again, go get some load resistors.

I got lucky; installed LED's in the third brake light and my cruise still worked. Not sure why I am so special. LOL

Originally Posted by green97

Ok why the front corners? I have a new flasher so no more hyper flash.

That just seemed to work the best for me. So passing that along to others. Will probably work in the rear tails as well. Did not work by adding load resistors to the third brake light.

Well I swapped back to regular bulbs in the third brake and got cruise back. Went to town and got new tires this morining. Had an alignment check and they found a bad wheel bearing so... bearings are taking priority. Getting to the point where I am asking what else can I replace? Got a new trans, engine w/new gaskets, f/r control arms, lights, alternator, belts/ tensioner /pulleys.