Troubleshooting Trailer LED Taillight Not Working On One Side

Question:

I have a 2005 Dodge Sprinter with your hitch installed. My trailer has LED lights. The van uses regular bulbs. Only one tail light lights. Brakes and turn signals work. A Hopkins power taillight converter is used.

asked by: Peter M

Expert Reply:

First you will need to use a Test Light # PTW2993 to test your 4-way vehicle connector to determine if your wiring issue is with the vehicle or the trailer. The tester has a probe feature that will allow you to connect into the wiring as well.

Test the connectors for proper function with the test light. Use the male ground lug on the 4-way to ensure that the ground is good. If everything is good move on to testing the trailer.

If you find a terminal that is bad you will want to test the wire behind the connector to determine if the connector is faulty. If the wire still has no power you can follow it to either the fuse box for a factory wiring kit or the converter/taillight for an aftermarket 4-way. If the convertor is getting signal from the correct light and not putting out power the converter is faulty.

To test the trailer first test just after the trailer connector to determine if the connector is bad. You can follow the power back to the taillight to determine if there is a short in the wiring or damaged wire. If you have power all the way to the taillight you either have a bad taillight or bad ground. You can clean the ground terminal to ensure that you are getting good contact with the frame. A jumper wire can be run from the ground circuit to the vehicle to verify that the ground is making good contact.

Finally you can bench test the taillight to ensure that you do not have a faulty tail light assembly.

expert reply by: Bud M