Troubleshooting Left Turn Signal on Wells Cargo Trailer Towed by Dodge Durango

Updated 10/26/2012 | Published 10/22/2012

Products Featured in This Question

Peterson Combination Trailer Tail Light - 6 Function - Incandescent - Square - Passenger Side

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$5.43

Hook Probe Circuit Tester

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$14.40

Question:

Hello, the left turn signal quit working but the tail light works. I switched bulbs from right side, same situation. My meter shows power when the turn signal is on, testing at the terminal the bulb fits into. Thanks in advance

asked by: John T

Expert Reply:

I would begin by troubleshooting the trailer connector on your Durango. Have a helper activate the left turn signal and use a circuit tester like part # PTW2993 on the connector pin that powers the left turn. If you have a 4-pole trailer connector, it is the pin fed by the yellow wire. If you have a 7-way connector, check the pin in the 9:00 position. With the turn signal active, the trailer connector pin should light up and blink along with the turn signal. This pin should also light up the tester when the brake pedal is pressed. If you do not get a signal on the pin, check the fuses that manage the towing circuits (see owner's manual).

Next, check the connector on the vehicle and trailer for damage and corrosion. Clean or repair as necessary. Make sure the connector on the vehicle and trailer are securely grounded, and that the point at which the ground wire is connected to the vehicle or trailer frame is not corroded. Trace the wiring leading from the connector on the trailer back to the stop/turn/taillight on the left side of the trailer. Check for any nicks or breaks in the wire, or any pinched wires or cracked or missing wire insulation that would allow the internal copper conductor to short out to the trailer frame.

Then, check the lamp itself. Make sure the lamp itself is tightly secured to the trailer frame, and that the mounting studs are in direct contact with the trailer frame or in contact with metal that is connected to the trailer frame. Closely examine the socket where the bulb installs for damage or corrosion. Make sure the bulb is fully inserted and locked into place.

I realize you have already checked a few of these, but there are only so many elements of the lighting system for a problem to occur, and they should each be checked as what is actually causing the problem can be very easy to miss.

You have tried swapping bulbs from one side to the other, try swapping the lamp temporarily. This will eliminate your left-hand lamp as being the problem.

Finding the problem will take a process of elimination, but we will eventually find it.

expert reply by: Mike L