Troubleshooting Brakes Locking Up On Camper  

Question:

Expert Reply:

Because of the "Pop" you heard, there may be a problem with the brake magnets such as being worn till the windings are visible. You will first want to do a visual inspection everything in that area for any signs of damage or excessive wear.

You can test the brakes by turning the brake controller to its maximum gain and have someone apply the manual override. If you use a circuit tester like part # PTW2993 on one of the wires leading to the magnet you should show current.

You can use a multimeter like part # PT89ZR to test the brake magnets. If the affected brake is not testing for function, then they will have to be replaced. I have attached a link to a helpful article that explains how to bench test the brake magnets you can check out.

If the brakes are testing fine, I suggest disconnecting the trailer to allow you to test the wiring on the vehicle independent of any potential issues on the trailer. You will also need a circuit tester or a multi-meter for this process.

First, test the 7-way. The brake circuit is carried on the pin at the 5-o-clock position (see photo please). If your controller is set for zero power and zero boost, in other words powered up but with no output level, you should detect close to 0 volts on the pin. If you detect 12V on this pin with the controller set to zero output then either the controller is bad or there is a short inside the 7-way or in the vehicle wiring.

7-way sockets and plugs can develop internal corrosion. This can be difficult or impossible to see from the outside. Over time moisture can migrate into the interior of these sockets and plugs and cause two adjacent circuits to become bridged together. Disconnect any wiring to the 7-way that you can and inspect it internally for any corrosive build-up or even just trapped foreign material like water, dirt or a stray strand of wire.

You can also test the trailer on its own using the car's battery or a spare 12V. When you apply this 12V battery power and ground directly to the contacts on the trailer's 7-way plug you should be able to hear and feel the trailer brakes engage. They should lock up or get close to locking up with this full power reaching the magnets. If the brakes do not respond in this way, then there is something wrong on the trailer side. You can also apply the battery power directly to the brake wire leads right at the wheel by cutting them; this test will bypass the trailer wiring. If the brakes engage when directly powered, then you know the issue is in the trailer wiring upstream of the brakes.

If you suspect your 7-way plug is corroded internally you can replace it easily and splice the other trailer wiring to it using a junction box kit like # HS381-9000. This includes a 7-way trailer plug, connectors, wire loom and junction box.

expert reply by: Timothy G

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