Troubleshooting Low Voltage To One Brake Assembly On A Trailer

Question:

I have Dexter 8k axles. I changed drums and backing plates on the left side about a month ago and did not change the brakes and drums on the right. The left side works good. I just changed the right side drums and backing plates and still the right side doesn’t grab as strong as the left. I checked voltage at the wire feeding the brake assembly and I only get 4 volts holding down the manual override at 10 with the truck stationary.these are the never adjust Dexter 12” backing plates. I have backed up in reverse hitting the manual override on and off. I drove the trailer for about 100 miles and still only the left side grabs. Should I disconnect the left for the right side to self adjust? I thought it’s not able to adjust because the left is pretty much doing all the work. Truck is 2021 F350 with built in brake controller. Thank you!!

asked by: Dan

Expert Reply:

Hi Dan,

If you're only getting 4 volts at the brake assembly when the brake controller is turned up then you have a wiring issue or a bad brake magnet. Since the other side is properly functioning I'd guess there's an issue with the wiring somewhere between the where it splits from the other assembly or with the brake magnet. You'll need to check the wiring and determine where the voltage drops in order to fix the issue.

Most likely since you have Dexter axles the wiring from the junction box runs to the left side first and then through the inside of the axle tube over to the other assembly. You can try disconnecting the power wire running through the axle tube and running a new jumper wire over from the left assembly. If that solves the issue then we know there's a break or damage to wire inside the axle tube.

expert reply by: Kevin C

Dan

5/13/2024

The wire doesn’t go thru the inside of the axle, it runs up top. If the truck is in park not moving and I hold down the factory brake controller at 10 what should the voltage be?