Trailer Dome Lights Do Not Work on a Haulmark Trailer Towed By a 2010 Chevrolet Silverado
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Question:
i have a 2010silverado and ahaulmark trailer all trailer lights work except the dome lights do i need to connect the red and black wire at the battery post is there a fuse inlie somwhere in the system that this wire connects to? do any changes need to made to the factory trailer connector?
asked by: Bob D
Expert Reply:
The first step to troubleshooting your trailer dome lights is to determine how the lights are wired. If your trailer has a 4-way connector, then they will be connected to the running light circuit. If your trailer has a 7-way connector, then the dome lights will be connected to a 12-volt auxiliary power circuit coming from the trailer connector.
If your trailer has a 4-way connector and the running lights on the trailer work, then there is an issue with the connection between the dome light and the running light circuit. The bulbs could be blown, the wires could have disconnected from the switch or the connection with the running light circuit could be bad. The best way to troubleshoot this would be to follow the wire from the dome lights to the running light circuit and, where possible, look for possible issues such as cut wires or loose connections.
If your trailer has a 7-way connector, then you will want to test the 7-way connector on your 2010 Chevrolet Silverado to ensure you are getting 12-volt power at the connector. Using a circuit tester like part # PTW2993, test the pin in the 1 o clock position with the vehicle on and off. If you do not have 12 volts at this pin, then there could be a couple issues.
Often times GM trucks require the connection of an additional wire under the hood. Located under the master cylinder/brake booster assembly will be the battery charge wire. This wire will be red/black with an eyelet on the end. You will want to connect it to the threaded stud on the front of the fuse box with an M8 hex nut, # 185917. I have attached a photo showing where to connect this wire. If this connection has already been made, then check for a blown fuse next to the stud.
If you do have 12-volt power at your vehicle connector, then the issue will be on the auxiliary power circuit on your trailer. Follow the wire from the connector looking for any loose connections or damaged sections of wire. If you are still unable to find the issue or a solution after following these steps, then let me know what you come up with so we can do further troubleshooting.

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