hot_runner58

Ok guys, so I bought this truck, they had a million in line wire splices and all sorts of crap going on with the pig tail wiring. Everything has always worked plugging my trailers in, but now the trailer brake won't work. When I step on the brake, it shows power to it in the way of a decimal coming up, but it doesn't bring up any numbers. Numbers, meaning the level of brake power being applied. So, is there a way to test if it is actually the brake its self not working, and not the wiring? I know it is in the truck, not the trailer its self, because I have tried it on my 3 flat bed trailers, and then hooked my other truck up to them and they all work with my other truck.

1-2-3

Hold a compass next to the trailer wheels. (a real compass, not one on your phone (just kidding)) Have someone step on the brake. If the magnets are getting power, the needle will move. What controller re you using? Is the controller using the factory harness or did someone run their own wire all the way to the back?

hot_runner58

I don't remember what brand it is. And right now it is getting the tranny fixed for the 2 nd time in 1k miles. New triple disc tc went out already. But I will look when it gets back.
The controller is hooked into a factory looking harness under the dash by the firewall.

So besides the compass, would it give me the same result just using a volt meter at the rear plug? Because as far as I can tell using it currently nothing is happening on the trailer.
But, if I get no volts at the plug, can I check just the brake in the cab to see if it is bad, and not a break in the wiring?

1-2-3

I know that my controller can sense if there is a trailer connected or not. So I don't know IF you can simply test it at the bumper plug with a meter. With situations like this...most likely...it's connection somewhere. Usually it's at the plug, either the truck side or the trailer side. I would start by looking at both. Look under the bumper and see if it's disconnected or dirty back there. Open the pigtail up on the trailer and look there, and look at the plug and socket. That may just be dirty. I keep some dielectric grease on my trailer connections. Keeps the junk and corrosion away. Also look at the wires behind each hub on the trailer. May simply be a bad ground there. Remember too that the magnets in the trailer hubs do eventually wear out and need replacing, but they do last a long time. When you send power to the trailer brakes, an electro magnet sticks to the inside of the drum and the force of the tuning drum wants to move that magnet, That magnet is connected to a lever that pushes the brake shoes apart. So just like brake pads, they do wear out and the windings are open so no current passes thru.

Busboy

The brake controller is an inertia style controller not a directly proportional one, meaning if the truck is stationary and you depress the brake pedal no slowing of the truck is sensed so no brake output to the trailer, if you use the slide lever on the controller that manually brakes the trailer. A direct proportional one like a Maxbrake gives a measure trailer brake output for a measured brake pedal input regardless of truck deceleration.

Colo_River_Ram

I keep one of the 7 ways in both vehicles, they make for quick and easy testing):

http://www.delcity.net/store/Trailer...Testers/p_9035

cLAYH

You'll need a multimeter that can test for continuity(BEEP!) and a long piece of wire.

Disconnect plug at back of controller, id the pin in the truck side of the plug that goes to the trailer plug at the back of the truck(usually blue wire). ID the pin in the trailer connector that is the the brakes. With meter set to OHMS or continuity attach one meter lead(doesn't matter which) to the plug under the dash and using the long wire touch the brake pin in the trailer plug at back of truck. Meter should BEEP! or show continuity or really low resistance, depending on meter and what it is set at. If it does, the wiring is good and I would check the brake controller, if you don't have continuity then the wiring is bad.

Don't have a meter? Use a test light, disconnect plug from controller, ground the blue wire on the truck side plug to a good ground under the dash. Then, at the plug at the back, attach the test lead of the test light to the trailer brake pin and probe the hot battery charge pin(B+) with the other end of the test light. Test light will light if wiring is good.

carl48

connect a head light or tail light up between the pins on each side of the notch on the 7 pin plug and use the side lever bar if it is inertia type. it will be the dark green truck wire.

cLAYH

That still won't tell if its bad wiring or the controller. He already knows he is not getting a signal to the back.

Busboy

He's not getting the signal to the back because he didn't use the slider, he just used the brake pedal.

cLAYH

Sorry, when he said he had tried it with the other 3 trailers, and the trailers with the the other truck, I figured he was actually out driving around with them.

Busboy

No worries, we often assume people know how stuff works and often the simplest thing can throw you off.