Hey, I am having a problem with my trailer plug and/or trailer wiring. When my running lights are off, the lights work fine...(turn signals and brakes). However as soon as I turn on my running lights, the light assembllys light up very brightly and stay this way regardless of applying the brakes or using the turn signals. Any ideas here. The grounds (truck frame from plug and trailer from plug, as well as the lamp assembly grounds appear to be good). The lamps I am using are multi function brake, running, and turn signal. Thanks.

 

Sounds to me like a ground on the trailer...hook up a test light and test your plug at the back of the truck...diagram is easily found online...if everything works that way, its definetely a ground on the trailer

 

Thanks, I will test the plug and if needed track down a ground.