Signal engages brakes

M

mr. black

New member
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.:shrug:
 
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.
 
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.
 
Greg may be right but do not overlook Josh’s suggestion. When electrics act unpredictable always suspect a bad ground.
 
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?
 
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.
 
Rewiring a Car Trailer

I agree with all that has been written above. Any pulsating light or brake assembly (when directionals are applied) will be a reflection of a bad ground someplace, allowing a different, unwanted path for the current to return to "Ground". Remember the basic rule of electricity, "Electricity will always follow the path of least resistance".

I only want to add, as one who has recently rewired an 18 foot open car trailer, it's a little time consuming, but really worth it. Traditionally, trailers are wired with "Scotch connectors" (a cheap method of taping into an existing wire with minimum effort), or what ever thay are called, that leave the connnections exposed to the elements (read corrosion). After a few years have passed, the owner will chase wiring problems from one part of the trailer to another.

I bought (NAPA) 5-wire loom in two 25 foot lengths (soldered together), strung one length down one side from the plug (front of trailer), across the rear, and another up the other side to the foreward most light. The wire is color coded for typical wires of the trailer, and I had an extra wire in the loom for the back-up lights which we installed upon purchase oh-so-many years ago. Very handy when returning at oh-dark-O'clock.

Using the wire loom, it gave the option to have directional lights on any location on the body of the trailer, not to mention axillary lights (Back-up lights) mounted anywhere. After the wire is in position, just tap into the appropiate color for that particular light (see next sentence). The key to the success of the job (and the most time consuming) is to solder all connections and cover with shrink tubing. Of course, if the chassis of the trailer is also used for ground (almost all are!), re-establish the ground connection with wire brush, sanding, good connections and dielectric grease.

This will also give you opportunity to check the wiring of the brake assemblies, which were also connected with scotch connectors.

If you devote a Saturday to this project, you will be rewarded with consistant lighting and braking for years to come. Braking efficiency is synonomous with Safety.

Good racing.

Bill:024:
 
Thanks. It looks like in the end it's better in the long run to redo than to chase. Meanwhile, I will look for that ground because I don't know if I'll be able to rewire before March. Come on spring, hurry up!
 
Would a pulse preventer do the trick and prevent having to rewire? Also, where can I find wire diagrams to wire a trailer for interior lights/battery etc.?
 
Dont let me ruin your day but.... Does the truck have seperate brake and turn bulbs,look at the module under the truck, also check your turn signal switch. There is a piece inside to stop the brake lamps from back feeding the front turn signals. Common on older Chevys. Could also be as simple as a bulb installed incorrectly.

Make a dedicated ground to the trailer,do not rely on the trailer ball. You grease that right?grease is an insulater..Good luck
 
Possible diagnostic method.

Let me enter the discussion one more time. Here is a possible path to solution.

Make up a jumper wire (single) with sharp pointy thing at each end (awls with alligator clamps to each), length determined by the trailer. With directionals, or emergency flashers (my preference) on, start at the hitch, and using the sharp point, make contact thru rust and paint with the chassis of the trailer, and put the other end on the tow vehicle. You are looking for the lights to stabilize...only the directional/flashers to work properly, and the other lights to remain with a steady glow.

Follow up at each light, stop/directionals and marker. If the main ground tested OK, each of the lights can be checked at its ground site. When you reach the bad ground area (assuming it is only one), the problem will go away.

If you are lucky when you do this: Correct the problem. Leave the rest of the wiring until later.

Good luck.

Bill
 
I will try that as well bilf. I hadn't noticed if the trailer lights were showing any signs. Mainly because I'm driving the truck. But I'll check it out.
 
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