Troubleshooting Trailer Brakes That Won't Release

Question

Question:

I plug in or not electric brake wont release. Light is not coming on on controller. Brakes wont release.

asked by: Mickrell M

0

Expert Reply:

If your trailer's brakes remain engaged when it is plugged in to your vehicle, even when the controller does not indicate that it is generating a brake signal, this most often means that there is a short in the vehicle's or trailer's connector.

What can happen is that corrosion (or water or trapped foreign material) inside either the vehicle socket or the trailer plug can cause two different circuits to become bridged together. This could, for example, allow the power for trailer lights to bleed over to the brake circuit, causing it to engage the brakes when they should not.

The best fix to this issue is usually a new trailer connector, such as # 37185 or # H20046, but sometimes the corrosion (if that is indeed the cause) can be dissolved with a spray-on electrical contact cleaner such as Caig De-Oxit. Clean properly-functioning connections can be protected with an application of dielectric grease like # 11755 which blocks entry of moisture.

Another potential cause is incorrect installation of the controller red wire. This wire carries the signal that triggers the controller to generate a brake power signal for the trailer. If this wire is connected to the wrong circuit on the vehicle it could cause the brakes to engage when they should not. This read wire should connect to the cold side the brake light switch, which is the wire that carries a signal ONLY when you press the brake pedal and at no other time.

expert reply by: Adam R

0

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Answer 1

You may be right. I would remove the assembly and check that all the components are in working order. See if you can get it to do the same thing while off the trailer by manipulating the various moving parts. Some of the parts may need to be…

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Answer 2

To determine the size of the brake assemblies you need you have to measure the depth and width of the hub drum on the axle like what you see in the picture I attached. The most common size is 2-1/4 inch wide like the #T4071600-500 that you…

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Answer 3

The 235/80R16 size tire, like the Karrier ST235/80R16 Radial Trailer Tire #AM34903, will measure about 30.8" for overall diameter and have a section width of 9.25". This tire/wheel combo has an 8 on 6-1/2" bolt pattern. If you need a…

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Answer 4

There are several ways that you can cut off the power to your trailer brakes. The easiest option would be to simply unplug your brake controller. If the brake controller is disconnected, the brakes will not receive power. If your brake controller was…

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Answer 5

For starters, I am going to assume that you have electric drum brakes. The issue you described of the brakes locking up could be caused by several different things. In order to save yourself some time, I recommend hooking up the trailer to a…

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Answer 6

One wheel locking up on your trailers brakes could be for a few reason. Most likely it's due to a brake assembly that is out of adjustment. You want to adjust the assemblies so there is only a light drag on them when they are turned by hand.…

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Answer 7

There are a few things you can check to make sure the brakes are adjusted correctly, but it sounds like there may be a short in the system. I would start by checking the trailer wiring connector on the truck and trailer for corrosion. If there is…

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Answer 8

Yes there will be a fuse that protects the 12 volt trailer accessory circuit of your 7-way wiring. If this is factory wiring of a truck you'll want to check out the fuse box diagram or the owners manual.

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Answer 9

I have a suspicion about what might be causing the problem you mention. Do your trucks have 6-way trailer connectors? Or, do the trucks have 7-way connectors, but you are using a 6-way to 7-way adapters because the trailers use 6-way connectors?…

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Answer 10

If your break away switch looks like #HM20010 then you should just have to push the pin back in. This will break the circuit and release the trailer brakes. If this does not work then there is some other wiring issue going on. You will need to remove…

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Answer 11

The first thing to check is the connectors to make sure there is no corrosion present. That can cause a variety of problems. If that checks out you will need to do some other testing. You can sever the blue wire about 4 to 6 inches from the back of…

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Answer 12

You are correct, you should only be getting output when the brake is applied, or the override switch is activated. It sounds like the controller might be bad, but to make sure, you should probably bench test it before tossing it. Use a circuit…

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