Trailer Brakes are Weak and Low Voltage and Amperage at Brake Magnets on 5th Wheel Trailer

Updated 07/29/2014 | Published 07/27/2014

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10 Gauge Wire - Blue Primary - Per Foot

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$1.78

12 Gauge Wire - Black Primary - Per Foot

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$1.61

Question:

I have a husky quest brake controller which is a Hopkins agility. with the controller set to 99 sensitivity 5 manual slide fully depressed voltage at truck plug is only 11.8 truck running.if I unplug the controller and put a jumper wire from the black hot to the blue it has 13 volts at the plug.is that normal to have a 2 volt going through the controller? at the wheel magnets 10.25 volts with controller and 11.5 volts jumped and still very poor brakes. when jumped amp draw is 12.5 amps and slowly drops to about 11.5amps. it is a 5th wheel camper 4 brakes 12 inch x 2 .the brake wires going through the axle looks very small maybe 16 or 18 gauge. any thoughts ?

asked by: Scott

Expert Reply:

A slight voltage drop between the controller and the magnets is normal. But you will need around 12 volts at the magnets for proper operation.

The only way to know the wire gauge is to strip away the insulation and measure just he copper strands. If it is 16 or 18 then that is way too small. You will want to go with 12, # 12-1-1 or 10, # 10-1-1 each sold in 1 foot increments.

The amperage is also low. With four 12 inch brakes you should be seeing 15-16.3 amps at 12-13 volts. It is possible that the magnets are bad. I have linked an article that explains how to test the magnets.

You may also want to adjust the trailer brakes. There should be a slight but constant drag of the pad on the drum when the wheel is turned. I have linked a video that should help with brake adjustment. Fast forward to about the 4 minute mark.

There are also some steps you can take to test the brake controller. I have included the links on testing and troubleshooting controllers.

expert reply by: Michael H