How To Test Trailer Wiring To Locate Problem With Left Turn Signal On 2006 Chevy Colorado

Updated 09/28/2010 | Published 09/26/2010

Question:

had hitch and wiring prof installed. 1-3 days later when I touch brakes the left turn signal blinks once very dim. returned vehicle, they replaced a part which had problems in the past they were aware of. 2 days later I have same problem. what can it be???

asked by: dennis s

Expert Reply:

If you have installed the Tow Ready T-One Wiring Harness, # 118301, you will want to use a circuit tester like part # PTW2993 and test the wires going into the converter box and the wires coming out of the converter box. This will help determine if the problem is on your 2006 Chevy Colorado, the trailer or with the converter box.

With somebody to turn on the turn signals and step on the brakes, test each wire to see that it is working properly. Also, make sure the ground is attached to a good grounding point. Next, would be to test the wiring coming out of the converter to the trailer connector on the vehicle.

If the wires going into the converter box are showing no signal that would mean there is a problem on the vehicle. You will need to check the fuses and all the wires to make sure they are connected properly on your vehicle.

If the wires going in the converter box test good and the wires coming out test good it will be a problem with the trailer wiring. Solve the problem by inspecting the wiring on the trailer to make sure all of the connections are correct and ground wires are connected properly.

Most likely, the ground wire on the trailer is not secured properly. A trailer wiring system is grounded to the frame near the coupler and each light also needs to be grounded. If there is not a white ground wire coming out of a trailer light the light is grounded through its mounting studs. Too much paint, dirt, or rust can cause bad grounds, so make sure the ground is secured to the bare metal frame. Also look for pinched or cut wires, these are often found when wires are routed above suspension components or behind taillights

If the wires going in to the converter box test good and if the wires coming out are not working then it is a problem with the converter box.

I am sending a link to information on trailer wiring and how to troubleshoot your trailer wiring.