Trailer brakes

[brianMO]

I built a trailer wire it carefully. When I hooked up the trailer brakes the controller appeared like it was happy. When I am moving and try to apply the brakes I get a OL on the controller. The brakes do not seem to work. I guess I will need to troubleshoot it over the weekend. It appears only two wires are involved, ground (white) and brakes (blue). I was told that the magnets are not polarity sensitive. Any ideas.

 

[RWolf]

Recheck your wiring. All of one side of the brake magnets gets tied to blue and the other side of the magnets gets tied to ground. If your getting an overload condition you might have a short in your blue side or a magnet is no good. The only other thing is to insure your controller will handle the number of wheels you have i.e. most controllers will handle 1 or 2 axles but if your using 3 then you need a heavier controller.

 

[Diamondpilot]

Re: trailer brake question

99% of the time its the grounds. Have you ever used this brake controller with another trailer? Maybe its bad? The mags are like you say, non polarity sensitive. Check all the wiring but really take a look at the grounds. I like to run mine all back to the same spot on the trailer for everything. Take a few more feet of wiring but eliminates problems down the road.

Chris

 

[George2615]

When you say it appears only two wires are involved are you talking about the controller in the vehicle or at the trailer. The trailer brake controller in the vehicle should have more than 2 wires. It needs at least 4, one connected to vehicle fuse box for power, one connected vehicle ground, one connected to brake switch of vehicle, one connected to trailer brakes. At the trailer plug end the blue wire will apply voltage to the brakes and use vehicle ground to complete the circuit. If all is correctly wired you probably have a trailer grounding problem.

 

[J_J]

I built a trailer wire it carefully. When I hooked up the trailer brakes the controller appeared like it was happy. When I am moving and try to apply the brakes I get a OL on the controller. The brakes do not seem to work. I guess I will need to troubleshoot it over the weekend. It appears only two wires are involved, ground (white) and brakes (blue). I was told that the magnets are not polarity sensitive. Any ideas.

Did you perhaps wire each side in series, One wire from each coil should be tied together, and grounded. The other wires should be tied together and that is the B+ /blue to activate the brakes. You can take a battery and jumpers back to the brakes and test them each or all together. Then go to the plug and put one wire to trailer ground, and the other to B+/blue/wire/ pin. Do you have an aux battery or break away battery, that also has to be wired in correctly.

Typical Vehicle Trailer Brake Control Wiring Diagram

 

[radioman]

first of all, we need to make sure the vehicle side works with another know working trailer. If the vehicle side works, then a wired ground needs to be connected directly to the vehicle and use it as a test right on the brake wires neutral to make sure the brakes are working. Once both sides of trailer brake magnets is confirmed its working with test ground, then the OP can work back wards towards the tow vehicle checking wiring.

 

[JohnDeere4300]

Re: trailer brake question

99% of the time its the grounds. Have you ever used this brake controller with another trailer? Maybe its bad? The mags are like you say, non polarity sensitive. Check all the wiring but really take a look at the grounds. I like to run mine all back to the same spot on the trailer for everything. Take a few more feet of wiring but eliminates problems down the road.

Chris

When i bought my trailer new i already had a brake controller, i went to haul my tractor and noticed that the brakes was not holding the way it should, the dealer worked on it and the brakes seemed better, but i had to turn my controller almost all the way up.

I hauled that thing around for two years until i had new tires put on
and noticed the ground wire just wrapped around a bolt, i grounded the wire better and could not believe the difference.

Now with a better ground i can turn my controller on half way, when loaded my trailer brakes will hold good, turned all the way up and the brakes will lock up and slide.

So Diamondpilot is right, it probably needs a better ground.

 

[J_J]

Re: trailer brake question

If you know how to use a multimeter, You can measure the resistance for each coil on the brakes, and from that find out how much current is being used. Then hook up the meter to read current and apply 12 v, and you will get a good indication if the brakes are working. I believe that the controller is a current limiting device, and therefore, applying the current you set to control your brakes. A little current, low braking action, full current, brakes lock up. Your trailer brakes should have about the same stopping power as you towing vehicle, so as not to push you down the road.

 

[MarkLeininger]

Re: trailer brake question

99% of the time its the grounds. Have you ever used this brake controller with another trailer? Maybe its bad? The mags are like you say, non polarity sensitive. Check all the wiring but really take a look at the grounds. I like to run mine all back to the same spot on the trailer for everything. Take a few more feet of wiring but eliminates problems down the road.

Chris

I can't think of any scenario where a bad ground could lead to an overload condition. An overload condition means too much current is being drawn. That can be caused by a short to ground on the hot side, or a bad magnet, or miswiring so the resistance of the brake circuit is too low, or probably other things, but not a bad ground. Bad grounds are frequently the cause of non-working brakes or poorly working brakes, but I don't see how it could cause too much current to be drawn.

 

[Diamondpilot]

Mark, you have a good point. In general trailer wiring problems are ground related. The only way I could see it causing that problem is if the ground is causing a lot of resistance.

Chris