Troubleshooting Trailer Wiring Issues

Troubleshooting Trailer Wiring Issues

You are doing a pre-check on your semi-truck before hitting the road and you notice some of your lights aren’t working. Do you rush it to the repair shop for a wiring overhaul? No, the first step is to troubleshoot the trailer wiring. Wiring issues are usually easy to solve and fall under one of the following categories.

Does the Problem Lie With the Tow Vehicle or the Trailer?

Disconnect the trailer from the tow vehicle. Test each one separately. For the testing, you can use either a jump starter pack or a standalone car battery.

Faulty Ground Connections

Weak or poor ground connections are the most common cause of wiring problems. Clean all connections to remove existing corrosion or paint build-up. Clean until you achieve clean metal.

If your ground screw is stacked with other terminals, move it to another location or towards the bottom. Another solution is to reconnect the ground wire to a wire that is connected to the car’s negative terminal. For the trailer, ensure that the ground wire connects to the trailer frame.

Alternatively, if the ground screw or ground wire is thoroughly corroded, replace it.

Check Fuses and Overloaded Connections

Test the fuses in both the tow vehicle and the trailer to determine where the fuse problem could be. If a blown-out fuse is a recurring problem, then your lights are overloading the circuit.

Check the maximum amperage rating of the harness, and compare it to the power your trailer lights draw. If your harness works without any lights, but shorts when all bulbs are present, there is an overdraw. Replace your clearance lights with LED bulbs. With their low voltage, they would quickly solve the overload issue.

Confirm Wire Connections and Terminals

The other common wiring problem is loose, crimped, or non-sealed connections. Crimp-only connections are often loose even when they feel tight. It will save you plenty of headaches to change all the crimp-only connections to crimp and solder connections which are more secure. Check for loose connectors or wires that are attached incorrectly.

You can also do a continuity test to check for broken wires. Select one color wire in the socket and trace the same color wire in the connector front. Clip one end of this wire to the connector pin and the other end to the continuity tester. If the trailer lights are dim, follow the wire, cut off any faulty bits, and solder new wire on. Repeat with the other color wires.

Remember to check if the bulbs have gone out and replace them as needed by screwing them off then on.

Corrosion and paint build-up can also interfere with the function of your trailer’s wiring. Make sure any aluminum areas are clean of paint and all corrosion has been cleaned off using electric contact cleaner and fine sandpaper. 

Mobile Truck Repair in Gainesville

Despite all the trailer wiring troubleshooting, you might find that the trailer wiring problem is much bigger than these simple steps. In such a case, don’t hesitate to contact Road Rescue’s mobile truck repair service in Gainesville. Road Rescue will come to you and carry out both trailer repair and truck electrical repairs in Gainesville


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