No Running Lights On Trailer But All Other Lights Work

Question:

Hi I just installed a T One Harness for my truck -works perfectly!! on my boat trailer and my friends utility trailer So All good with tow vehicle Now - I have another trailer 12 ft long utility steel frame New lights -Stop Turn and Tail all work great except for -***** NO Tail Lights****** have redone the ground even swapped out trailer harness with new one - Same Issue no running lights????? The lights are supposed to self ground?? HELP

asked by: Kevin D

Expert Reply:

If the running lights do not turn on then you have a short in this circuit, somewhere between each light and the trailer connector and this circuit is usually carried on a brown wire. Therefore, you will need to trace this wire from each light up to the trailer connector while checking for breaks.

That said, if the running lights work at first but then cut out when you have other signals activated then this would be a ground problem. I recommend you sand down the surface in which the light attaches or just run a jumper wire up to the main trailer ground for each light to see if this fixes your issue.

The running light pin on the trailer connector may have corrosion on this as well.

expert reply by: Conner L