Troubleshooting Left Turn/Brake Lamp on Trailer Towed by 2007 Ford F150
Updated 08/29/2012 | Published 08/26/2012
Question:
2007 ford 150 left trailer brake and turn signal does not work. Tail lights work with head lights on, If I hook right turn and brake light to left trailer tail light it works fine. Check the fuses and fuses are okay. Doesnt look like I can get power back to the Left break and turn signal on the trailer. Not sure what else to try. Any suggestions.
asked by: David J
Expert Reply:
As a first step, you will want to determine if the problem is on the vehicle or in the trailer wiring.
Use a circuit tester like part # PTW2993 and test the pin on the trailer connector fed by the yellow wire while the turn signals are activated. This pin should light up with the turn signal and when the brake pedal is pressed. If this pin does light the tester, the problem exists with the trailer wiring. You will need to trace yellow wire that feeds the driver's side turn signal and brake light rearward from the trailer connector, looking for pinched or broken wires. Look for cracked or worn wire insulation that would allow the copper conductor to short out to the trailer frame. Make sure the connection to the lamp is secure and not corroded.
If the tester does not light up, there is an electrical problem of some sort on the vehicle. Some Ford trucks will have some tow package fuses located in a small junction box on the firewall. Because the fuses are separate from the main fuse box, they might have been missed when you were checking fuses.
