Troubleshooting Trailer Tail Lights that Dont Work with Brake and Turn Signals that Work

Updated 04/23/2018 | Published 04/20/2018

Question:

no trailer tail lights,got turn signals,brake lights just no trail lights on trailer,

asked by: Billy

Expert Reply:

First start by checking any fuses related to towing and replace any that need it.

If it's not a fuse use a circuit tester like our # PTW2993 at the vehicle's trailer connector while someone else is operating each function. This will isolate whether the problem is with the vehicle or the trailer. If everything works okay at the vehicle's connector, then the issue on the trailer side.

Once you know whether it's on the vehicle or the trailer inspect that connector for any damaged pins, dirt, or corrosion. You can try cleaning the connector. If the problem isn't with the connector then it's either a bad ground or a short in the wiring itself somewhere. Make sure the ground connections are to good, clean, bare metal surfaces.

To check for a short you'll need to start at the connector and either trace the wiring towards the front of the vehicle or torwards the back of the trailer. Whichever you found to be the culprit earlier. Look for any damaged or pinched wires.

If you still can't find the issue let me know what results you've gotten from the tests and we'll keep troubleshooting.

expert reply by: Charles S