Troubleshooting Turn/Brake Lights on Trailer Not Working

Updated 10/23/2018 | Published 10/22/2018

Products Featured in This Question

Hook Probe Circuit Tester

(72)

$13.44

Dielectric Grease for Electrical Connectors, 2 oz.

(1511)

$9.54

16 Gauge Primary Wire - Black - Per Foot

(64)

$1.01

Question:

I just bought a 2012 Wildwood travel trailer, the seller said when he bought it, all the lights worked, however when I went to drive it off their lot, the normal running lights worked all over the trailer, but the blinkers and brake lights did not. What can I check. We already checked the fuses on my truck, that we thought could be a correct fuse, and all seemed o.k.

asked by: Steve R

Expert Reply:

Normally when one function works but others do not, it has to do with a bad ground connection. I recommend using a circuit tester like # PTW2993 to check each pin of your truck side connector for function first. Clean all the blades with some sandpaper and use some dielectric grease # 11755 to protect it from corrosion and moisture. I've attached a photo to help with function locations.

If that checks out, then connect the trailer and check the ground location near the coupler and battery to make sure it is clear of all corrosion, rust, and debris and is bare metal to metal. Next check the ground locations at each taillight. The taillights often use the mounting hardware as the ground for their functions if there is not an independent ground wire. Make sure these connections are also clean and bare metal to metal.

If that doesn't solve your turn/brake light issue, then I recommend using the circuit tester to test the wire function every couple of feet to find a short. Replace with # 16-1-1 wire as needed.

expert reply by: Jason S