Tail Light Stays on with Trailer Disconnected
Question:
Hello, I have a 2007 Haulmark trailer that I recently purchased used and it has an auxiliary battery that was added on the front for interior lighting use without the need of a vehicle being connected. All functions of the wiring/trailer work great when plugged into the 7 Pin of my truck. The auxiliary battery has the negative terminal grounded to the tongue of the trailer. The positive terminal has a lead that is spliced to the black 12V of the trailer. Thus it charges the battery when connected to the truck and provides power to the interior lights when not connected to a vehicle. The issue is that for some reason the auxiliary battery is powering the right tail light for some reason causing the battery to drain. I have confirmed that the other wiring is working well by providing power to the Green/ tailand running lights, as well as the Brown /right turn/stop. Any advice would be helpful. They are LED lights and as far as Im aware all lights on the trailer are grounded to the trailer. I recently replaced the interior lights and they were grounded to the frame. Same thing with 5 of the running lights I had to replace. Thanks in advance!
asked by: Levi
Expert Reply:
There are only really two things that could be causing the auxiliary battery to illuminate the tail light which is either a short in the tail light wire or corrosion on the trailer connectors. For starters, the easiest thing would be to look at the pins inside the trailer connectors on both the vehicle side and trailer side. Make sure none of them are bent or have any corrosion on them. If they are bent you can take some needle nose pliers and straighten them back out. If they are corroded then you would need to take so electrical contact cleaner and spay them down. Once this is down you would also need to pay special attention to the wires leading into the trailer connectors to make sure none are touching one another.
After the trailer connectors have been checked the only other thing that is left to do is trace the right side tail light wire from the trailer connector back to the light assembly while checking for any bare or exposed wire. This will need to be either repaired with some electrical tape or replaced entirely.
I can't really think of any other reason that would cause the auxiliary battery to illuminate the tail light so one of the above should fix your issue but if it does not please let me know.
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ZCI Circuit Protected Vehicle Wiring Harness w/ 4-Pole Flat Trailer Connector and Installation Kit
- Custom Fit Vehicle Wiring
- Trailer Hitch Wiring
- Converter
- Universal Fit
- 4 Flat
- Tekonsha
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