Trailer Lights Don't Work When Headlights are On
Updated 11/01/2024 | Published 07/06/2015
Question:
when headlights are on trailer signals will not work,but work fine when lights off. i checked grounds and connections. all seem good ?
asked by: Greg
Expert Reply:
The problem you are having is a classic ground issue. If the ground wire to the trailer frame or the tail light grounds are not connected securely to clean, rust and paint free surfaces then when the headlights are turned the extra amperage draw for the running lights will cause all sorts of lighting issues.
I would start by removing the ground wire at the trailer coupler and cleaning up the connection point and re-securing it to the trailer frame. Next I would check the ground connection of the trailer lights. Usually they are grounded through the mounting bolts for the lights. Make sure that the connection is clean and free of paint, rust and debris and, if there is a plastic license plate holder on the drivers side, make sure that it is not inhibiting the lights ground. Finally if the trailer light mounting brackets are bolted to the trailer frame you should remove them clean up that connection point also.
These simple steps should get you going and ensure that your trailer lights will work properly.
Tony
10/28/2024
And of that doesn't fix the issue, then what? I have the same problem. Brand new pole lights. Brand new wire harness. Brand new harness adapter.Everything is wired and grounded correctly. Also, all of the bulbs in the new pole light fixtures are not illuminated.
Jameson C.
11/1/2024
Product Page this Question was Asked From
Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector
- Custom Fit Vehicle Wiring
- Trailer Hitch Wiring
- Vehicle End Connector
- Converter
- No Tow Package
- 4 Flat
- Plug and Lead
- Plug-In
- Visible
- CURT
more information >
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Patrick
5/25/2024
I have the issue that the left turn signal on the trailer does not work when head lights are on. I checked continuity with multimeter- all good. What else could this be?
Jameson C.
5/27/2024