Why Don't Some Trailer Light Functions When Blinkers are On

Question:

I installed new 3/4 led running lights and new 6inch oval led tail lights to a brand new 4 pin wiring harness. The problem I am having is when the turn signal is on the brake light does not come on but the other side brake light is working. Left turn on no left brake light, right brake light is active. Right turn on no right brake light, left brake light active. Hazards on no brake lights active both sides. Turn signals and hazards off everything works how it should. Also installed 3/4 side turn signals they come on solid when brakes applied. Side turn signal on still flashes when brakes applied. Turn signal off they come on solid with every press of the brake pedal. If its solid while applying brakes and I turn on the turn signal it will flash how its supposed to.

asked by: Joseph E

Expert Reply:

As odd as it may sound the problem is you have a weak ground on your trailer wiring. Try improving the connection from the ground circuit of your trailer wiring connector to the frame of the trailer and also make sure the grounds of the light assemblies are making a solid connection. You may need to run a jumper wire from the assemblies back to the main ground harness.

expert reply by: Jameson C