Troubleshooting Rear Lights On Tow Dolly Not Working When Connected To RV

Updated 04/12/2021 | Published 04/08/2021

Products Featured in This Question

Hook Probe Circuit Tester

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$13.43

Question:

Rear lights not working thru tow dolly wiring from RV.

asked by: Steve L

Expert Reply:

I would be happy to help!

Since the tow dolly has built in lights and either a 4-way connector or 7-way connector depending on if the dolly you have has electric brakes or not, there are a few things to test.

First using a circuit tester like # PTW2993 you will want to test the connector on your RV to make sure power is making its way through the connector. You will want to have a buddy operate the turn signals, running lights, and brake pedal while you check each of the pins for power.

If you have power this tells us the issue is on the dolly side, if you do not have power you will need to check the fuses in your RV to double check that they are installed and not blown.

If you have power to the connector, take a look at the connector on your tow dolly and make sure that there is no debris or corrosion in the connector causing the lights to not work.

Next check the main ground on the tongue of the dolly to make sure it is still tight and isn't rusted or corroded.

If the lights on the dolly are still not working, you will need to use a circuit tester to check each wire running from the connector to the lights, trying to find where the power stops. If power is making it to the lights, make sure the grounds for the lights are secure.

I included a link to a helpful article on trailer wiring for you to take a look at.