Both tail lights flash

[David Forrest]

I have upgraded to all led lights and replaced the relay. They have been working great. About a week ago both rears started blinking together. The front and dash blink like they should. I have checked the wiring in the rear and cannot find a problem. I did find out if I connect my trailer they work properly. Any ideas would be great.

 

[Chris]

Sounds like it's a ground issue most likely. The taillights are grounded to the tub, so that's where I would look first.

 

[David Forrest]

Just checked grounds again both sides are getting good ground.

 

[David Forrest]

Turns out it was a bad connection in the plug going to my trailer light outlet.