Troubleshooting Aggressive Braking Force on 2012 Coachman Freedom Express Travel Trailer  

Question:

Expert Reply:

Any trailer brake controller, if it is functioning correctly, will output the power level you have selected via its power and boost controls. This is true for both the time-delay type and for the often-preferred proportional type, such as the prodigy P2 # 90885.

Since the problem seems to have self-corrected after you washed the trailer this makes me suspect that some sort of wiring problem on the trailer is the cause. You do not mention if the controller's adjustment capability returned after the washing. If this did happen then this would make me suspect that there could be a corrosion issue in the vehicle's trailer wiring or that the controller has an intermittent internal fault.

What could happen is that corrosive build-up accumulates inside the trailer socket on the vehicle. In some cases this can cause adjacent circuits to be bridged together. If there were a corrosion issue - or even a stray strand of wire trapped between the contacts - this could let power from the trailer 12V power circuit bleed over to the brake circuit. This would allow full 12V power to reach the trailer brakes regardless of what the power setting is. Corrosion can happen on the exterior contacts or inside the housing where it can be very hard to spot.

You can test the brake controller easily enough by using a circuit tester like # PTW2993 or better yet a multi-meter that reads voltage, like # PT89ZR. Do this without the trailer plugged in since this will eliminate that other variable from the test. Set the controller to maximum power and maximum boost and apply the manual over-ride lever while you test for voltage on the controller's blue output wire. With the controller set to maximum power you should read at least 12 volts on the output wire. If you detect this approximate voltage, then reduce the power and boost to about 1/3 of the maximum. The specific voltage you read in this case should naturally be lower than with the unit set to maximum power. If not, I would suspect the controller has an intermittent internal fault and should be replaced.

You can also test the trailer by itself by disconnecting it and applying 12V power direct to the trailer brake circuit on the 7-way plug. Please refer to the other photo I linked for you that shows which contacts on the 7-way provide ground and the brake circuit. You can use the tow vehicle battery or any well-charged spare 12V vehicle battery to apply power directly to the brakes circuit. With full 12V power reaching the brakes you should be able to hear them gently humming and depending on the adjustment of the pas pressure feel the wheels lock up or at least have substantial drag on them.

You can also check the pressure adjustment of your brakes. The will have an adjustment wheel below the magnets, called a star wheel, that can be rotated with a tool # W80630 to reduce or increase the pad pressure and so the stopping force. The brake pressure could potentially be too high.

Please refer to the two linked articles for more on testing and troubleshooting trailer brakes.

expert reply by: Adam R

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