Signal engages brakes

[mr. black]

Back again. I have an enclosed car hauler. Sometimes when you turn on the signal light the trailer brakes engage in sequence with the signal creating a herky-jerky turn. Sometimes it happens by applying the brake. I tried cleaning out the 7 pin connector and that seemed to have worked on an occasion or two but not consistently enough to say that is the problem. Any advice? I will be doing a complete going over in the spring, including adding a brake controller and rewiring to fix the interior lights as well. (any info on interior lights and supplemental battery install would be great) Thanks.

[Greg Amy]

Somewhere in your wiring loom is a short between wires, the stop lamp power wire and the electric brake power wire. As your truck turns on the signal lights, it's also powering the electric brake(s). See if you can isolate the problem to one or both brakes; if both it's toward the front; if only one it's aft of the split.

Regardless, trailer wiring is usually of low quality and poorly installed. Honestly, your best bet may be to replace the whole shebang...it's not difficult nor that time-consuming...

Discussions on interior lighting and supplemental battery installs can be quite time-consuming and are best done over beers...but we just went through that so we can offer some advice.

Fix the basics, first.

[JoshS]

I'd guess a bad ground somewhere.

[almracing]

I agree with Greg. Sounds like the turn signal is shorting to the brake. I suspect it may be a build up of corrosion... because if it was a solid short, the brakes would probably lock up the wheels. Check the back side of all your connectors for corrosion.

[dickita15]

Greg may be right but do not overlook Josh’s suggestion. When electrics act unpredictable always suspect a bad ground.

[mr. black]

I've looked for a bad ground and I looked for corrosion. The only thing I found was that the contacts had been wet. I blew it out and sprayed some electical connector cleaner. It worked once or twice or for a little while. I may just redo the whole thing and include the interior and battery back up etc. Is this expensive and is there a recommendation other than just running bulk wire? i.e. does someone like Painless make something specific?

[Streetwise guy]

Pull the connectors apart at the bumper and make sure none of the wires have pulled out at all. Mine was a wee bit short, and would pull on the harness on hard jacknife turns, causing your problem.

Everybody else is correct about trailer wiring being crap. It could be anywhere.