Troubleshooting Camper That Has Working Clearance Lights But No Taillights

Published 09/24/2026

Question:

why my camper clearance lights work but brake ,turn signal and tail lights dont

asked by: Tony C

Expert Reply:

Hey there Tony.

Do the taillight assemblies also light up when you turn the headlights on like the clearance lights do? If so, that tells us the running light circuit is working and the issue is just with the brake/turn signal circuits.

If the taillight assemblies don't light up at all, then you may have a wiring issue, such as a ground wire that isn't connected or doesn't have a good connection. Even a little corrosion at a ground connection can cause problems like this.

I'd take a circuit tester like # TS25ZR and first test the functions at your vehicle's trailer connector. If everything checks out there, move down the trailer wiring and test the wires at different points to see where you're losing the signal.

Keep an eye on the ground wires as well, which are usually white and connected to a clean, bare metal surface on the trailer frame.

Let me know what you find out.