Headlights switch turns off cruise control

While driving home today, I was using cruise control set. It was getting dark so I turned on the headlights which caused the cruise control stopped working. I turned the head lights off and the cruise controlled worked again. The happens every time I turn headlights on. Any ideas why?

 

I’d check the tail and brake lights to see if both are functioning correctly. I suspect you have tail light power feeding back on the brake light circuit, either from a short between those 2 circuits, an open circuit to ground, or from LED tail light bulbs.

 

Thanks for the quick reply.

I just installed tail/brake led lights. I can put the originals back in to verify. If that is it, is there a led light that will work without causing this issue?

 

Sound like a missing ground in the taillights. taillight circuit feeding +12VDC throught the socket then to the brake light feed.

 

I had confirmed that the LED light installed was causing the problem with the cruise control due to crosstalk between the taillight and the stop light circuit. I tried to find a LED bulb that had crosstalk protection but I didn't find one. So I decided to install a diode in the brake light wire on each side to stop the crosstalk. After I installed the diodes, I test drove the truck and the crise control worked correctly. Stays on even with the headlights on. I've attached a diagram of the circuit. The diode I used is a 1N5402, 3 Amps at 200 volts. This leaves plenty of head room for the diode.

 

Thank you for this. I thought I was the only one having this issue after installing LED tail lights. For me, with the lights off and cruise control on, no issues... with the lights on, with cruise control on, when i use the left turn signal, the truck drops out of cruise control and shifts i to 4th gear. I tested it without cruise control, and when I press the left turn signal, it down shifts to 4th until releasing the turn signal....then back to 6th.

I think I'll just put the stock bulbs back in.
I am already using load resistors on each side and that isn't fixing it.