I have a baffling electrical problem I have somehow inherited. Was wondering if any of you have encountered this and if there is an obvious solution.

1999 Sundowner 4H, 14 ft shortwall. The problem is the passenger side brake lights (it appears to be the brake lights, could be tail) on the rear are staying on even when you unplug from the truck. Brakes don't seem to be locked up at all. I disassembled the plug to see if there were some wires that had somehow touched. After separating all the wires the lights are still on.

Is there something simple that I have missed? Seems like a wire has somehow been touched somewhere from the coach batteries.

This is not my trailer. I am just trying to help out a friend. I really don't want to trace every wire in the trailer. Simple wiring I can handle but when it comes to reading an OHM meter I get somewhat befuddled.

Thanks in advance for any advice or suggestions.

Thanks Michael,

That is the first thing I did. No wires touching and the lights stayed on.

 The plug wires go to a junction strip located on the trailer. I would check there. Somehow you're getting power from your trailer battery. It has to be at a point where the battery power (b+) and tail light wires are in proximity. I would check any common areas.

Gard

Thanks,

I am afraid that this problem lies somewhere in the channels. I did have one person mention to check the break-away switch on the gooseneck. I can't see how this would keep lights on and not activate the brakes but maybe I am missing something.

If you have a light switch (s) on the back of your trailer for stall or loading lights, there is a power source that runs all the way from the forward trailer bulkhead. Somewhere in that run, the running light power source and the stall light feed wires are probably shorted together.

As Richard indicated, any recent work or additions made to the trailer, that would involve that wire chase area, should be suspect. It may be that the installation of new wiring will be necessary.

If you can get the power wire colour at the rear light switch, go to the forward ingress area and locate the other end. If this can be disconnected, do so, and inspect the taillight for illumination. If  it is no longer illuminated, the stall power light wire is the source and cause.

The short could also be in the rear of the trailer where the stall light switches and the tail lights are in close proximity, with the wires running in a common chase. Again I would look to where ever some work has been accomplished

Gard

Thanks Gard,

The rear switches is  a good place to start. There is quite a few wires running pretty close in that channel.

I have asked if there has been any recent repairs or changes to the trailer and the answer has been negative. This trailer has been up and down the road a few (read many) times so the likelihood that a couple of wires could eventually rub together is pretty strong.