Trailer Running Lights Not Working when Connected to 2015 Jeep Cherokee Trailhawk

Updated 04/13/2015 | Published 04/10/2015

Products Featured in This Question

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

(267)

$67.47

Hook Probe Circuit Tester

(60)

$12.41

Question:

after installing i have all lights working...except the running lights. Tested the trailer lights on brothers car and the running lights worked for him. at a loss here. triple checked all connections. installed on a 2015 jeep Cherokee trailhawk

asked by: Tom

Expert Reply:

The first thing you will want to do is isolate where the problem is. To do this you will disconnect the trailer from your 2015 Jeep Cherokee. Then use a circuit tester such as # PTW2993 to test the 4-Way connector on the vehicle while someone goes through the light functions.

If you are getting power on the running light pin, then the issue is on the trailer. But if there is no power on that pin then you will need to test the brown input wire going into the converter box in the wiring harness.

If there is power on that brown wire going into the box but no power coming out then there is a problem with the wiring harness, and it will need to be replaced. If there is no power coming into the converter on that brown wire then the issue is on the vehicle side, possibly a blown fuse or bad connection where the harness plugs in.

Also check to make sure the white ground wire is secured by itself to a bare metal surface. No paint or coating can be on the surface, and it needs to be steel.

It is also possible that the trailer running lights are drawing more power than the wiring harness can handle. Provided there is power on the running light pin on the 4-Way, what you can do is disconnect a few running lights on the trailer, plug the trailer in, and see if the other running lights light up. If they do, then it is most likely an overdraw issue and switching to LED lights would reduce the draw.

The issue could also be a bad ground on the trailer. The reason that it works with another vehicle does not eliminate the possibility of it being a bad ground on the trailer because different vehicle wiring harnesses have different tolerances for that sort of error.

Make sure that the vehicle side and trailer side connectors are clean and free of corrosion inside and out. The main connector grounds should be attached to clean and corrosion free bare metal surfaces.

The light grounds should also be attached to clean and corrosion free bare metal surfaces. If there is anything between a light ground and the metal trailer frame or if the trailer has an aluminum frame, tilt bed, or folding tongue, any of these things can interrupt the ground. Running jumper wires from the light grounds to the main trailer connector ground can help.