Left Side Trailer Running Lights Not Working and Running Lights Blink with Turn Signals

Question:

Ive wired up a trailer with all new hard wear.... found out that the running light from tow vehicle has a built in 1 in the fuse box..i was told the only way to fix that problem was to replace the entire fuse box... Or run a hot wire from the battery using a fuse link and attach that to the vehicle side of the plug... did that and that worked... sense then Ive gotten another tow vehicle..... all the lights were working fine... until now ..... the left side running lights along with the orange running light and the center running lights all do not work.... only on braking, turning and hazzards do they all work.... the other thing is that when the turning signal is applied or the hazzads that the orange and center lights flash.. I have sanded down all the metal contacts for where they ground them selfs to the fender checked all the bulbs and all are fine . checked all of the connections and they are fine...

asked by: John

Expert Reply:

When some of the lights are not working and when lights activate that should not activate that is an indication of a ground issue and likely a short as well.

It sounds like you have addressed the potential ground problem but there are so many grounds on a trailer that you would need to check them all.

But the first thing I would do is make sure the vehicle and trailer side connectors are clean and free of corrosion inside where the wires attach and outside on the pins.

The light and main connector grounds should also be attached to clean and corrosion free bare metal surfaces. If there is anything between a light ground and the metal trailer frame or if the trailer has an aluminum frame, tilt bed, or folding tongue, any of these things can interrupt the ground. Running jumper wires from the light grounds to the main trailer connector ground can help.

expert reply by: Michael H