Troubleshooting Dim Tail Lights on Boat Trailer

Question:

I just recently re wired a new harness into the boat trailer because of so many splices . Anyway... the trailer has two marker lights up front , two marker lights on the fender, and an extra tail light in between the brake lights. I thought I wired them correctly but the marker lights are bright and the extra marker light in the rear and the brake,turn and tail are dim . Please help. I took my time and polished to bare metal for ground and added dielectric grease and shrink tubing for all connections. And now this. Lol. Where did I go wrong?

asked by: Steven B

Expert Reply:

Although it sounds like you have already checked this, the most common cause of dim trailer lights is indeed a weak or bad ground somewhere on the trailer. If the ground wires all look good, then you may also want to check the ground connections for the tail light assemblies themselves. A lot of trailer lights won't have a dedicated ground wire, but will instead ground through their mounting hardware. Just the same as with a ground wire, you will want to make sure that that they are installed on a bare metal surface and there isn't anything between the hardware and the frame such as dirt or corrosion.

I also recommend checking both the vehicle side and trailer side connectors for any dirt or corrosion that might be built-up behind the pins, simply cleaning out as needed.

Lastly, it's possible that the combined power draw of your trailer lights is simply a bit too much for the wiring harness on your tow vehicle to handle. If this is the case, then switching to LED lights on the trailer, which require far less power draw, might solve the issue. I have attached a link that will take you to our available selection of LED trailer lights that you can look through.

If you are still unable to resolve the issue, please let me know and I will be happy to look into this further.

expert reply by: Chris R