Trailer Lighting Malfunction After Installing CURT T-Connector Vehicle Wiring Harness # C59236

Updated 04/23/2014 | Published 04/21/2014

Products Featured in This Question

Curt Powered Tail Light Converter with 4-Pole Flat Trailer Connector

(1704)

$80.33

Hook Probe Circuit Tester

(62)

$13.94

Question:

Curt C56160 T-Connector Recently installed, turn signals on trailer flashed opposite of vehicle, rechecked all connections and ground but found no problem ... removed fuse for 30 minutes and turn signals correctly flashed ... now trailer brake lights remain on constantly and when brake is applied the turn signals switch to flashing opposite again.

asked by: Jeff H

Expert Reply:

First verify that the left- and right-side T-connectors are inserted fully into the vehicle connectors and that you have the correct left and right plugs connected. The connector with the yellow wire connects on the driver's side and the connector with the green wire connects at the passenger side taillight.

Next, I suggest you find a new location for the white ground wire. A weak or marginal ground can let some functions operate properly sometimes but may still be the cause for the erratic operation. Preferably use an existing grounding point for the vehicle's OEM wiring, but if one is not available select a new location that is a clean bare metal surface and carefully install the ground ring terminal. You can sand off the paint at the grounding point if necessary. The ground must be tightly affixed to this clean bare metal surface.

You can also disconnect the trailer to test it by itself using a 12V battery. This will allow you to confirm that the trailer wiring is not causing the issue. Apply a wire from the negative terminal on a spare battery (or the vehicle's battery) to the ground on your trailer-side connector and the +12V power lead one at a time to each of the other pins on the 4-pole while you watch the trailer's lights.

The linked article on troubleshooting 4-pole installations may also be useful to you. A circuit tester like # PTW2993 can also simplify testing. This will enable you to confirm that the vehicle is sending the correct signals to the converter box and that the correct signals are coming out of it.

expert reply by: Adam R