Troubleshooting Trailer Blinkers that Only Work When Brakes are Applied

Updated 08/01/2014 | Published 07/31/2014

Products Featured in This Question

Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

(218)

$55.21

Hook Probe Circuit Tester

(65)

$12.94

Question:

Hi, I have a 1993 Toyota Pickup, 3.0L V6 engine, I have this connector installed and I have working brake lights, working running lights but problems with my signal lights. If I turn on the signal lights with the brakes pressed they will work properly, if I turn on the signal light without the brake lights pressed they do not work. The lights on this trailer work without issue when connected to another truck that came with a factory installed trailer hitch and wiring.

asked by: Ryan

Expert Reply:

This could be a ground problem. A bad ground connection can cause all sorts of problems. First check the trailer connectors on the vehicle and on the trailer for any dirt or corrosion and clean them out. Corrosion can also build up behind the connectors where the wires attach.

On the vehicle side, make sure that the main ground is attached to a clean bare metal surface on the frame. On the trailer side connector, again make sure that the main ground is attached to a clean metal surface.

Use a circuit tester like # PTW2993 if needed to test the pins on the vehicle connector without the trailer connected to see if the problem is on the vehicle or on the trailer.

I attached an FAQ article on trailer wiring and 4-way installs for you to check out as well.

expert reply by: Jameson C