Troubleshooting All Trailer Lights Flashing When Vehicle Turn Signal Is Turned On

Updated 09/07/2021 | Published 09/06/2021

Question:

Hi, Ive got a boat trailer with a 4 pin wishbone plug and a 4 wire 4 pin vehicle plug. When I put on either signal light all the trailer lights flash. Ive tested the vehicle plug and confirmed its working properly. Ive followed the tips youve given to others but still having the problem, assuming a ground issue. I ran jumper cables from the trailer to the vehicle but still have the issue, so thinking its not the ground wire itself. Any suggestions in what to look for one the trailer itself? Thanks!

asked by: Stu M

Expert Reply:

I am sorry to hear about the issues you are having with the lights on your boat trailer!

Based on the issue you described it does indeed sound like there is a ground issue. You mentioned your trailer is a boat trailer, would it happen to be made out of aluminum?

Typically aluminum is harder to get a good ground on and to combat that you will need to run a jumper from each light ground to the main ground on the tongue of the trailer.

If adding the ground jumpers does not fix the issues just let me know and we can go into more in-depth troubleshooting steps.

I included a link to a helpful article on wiring for you to take a look at.

expert reply by: Samuel C