Troubleshooting Right Turn Signal Not Working On Enclosed Trailer Being Towed By RV  

Question:

Helpful Expert Reply:

The best way to check a relay is to use a relay that you know is good and insert it into the suspected relay's spot.

The first step would be to determine if the problem exists on the RV or on the trailer. Use a circuit tester like part # PTW2993 on the trailer connector at the rear bumper of the vehicle. Have someone activate the right turn signal, and for a 4-pole trailer connector, test the pin that is fed by the green wire.

For a 7-way trailer connector, test the pin in the 3 o'clock position. Pressing on the brake pedal should also light the tester. Turn on the RV head lights and check the running light pin. On a 4-way it is the pin fed by the brown wire. On a 7-way connector, the pin is in the 11 o'clock position. Check for damaged pins or any signs of corrosion or dirt and fix as needed.

If everything checks out the problem is in the trailer wiring. If the right turn, or running light pins do not light up when each function is activated, the probable cause is a blown fuse or a loose wire somewhere on the vehicle. Fuse locations can vary by vehicle. If the fuses check out OK, examine the trailer connector for loose wires or connections.

Next check the trailer connector, looking for corrosion on the pins or sockets. Corrosion can prevent voltage from the tow vehicle from reaching the lamps on the trailer.

Make sure the white ground wire is securely grounded to the trailer frame, and there are no signs of corrosion. Check the wiring, especially the green wire that typically feeds the right turn and brake lamp. Look for a loose or broken wires. Check that the wire connections at the lights are secure. Check the bulb and the socket for signs of corrosion.

expert reply by: Jeffrey L

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