Low Voltage to Trailer Brakes After Installing New Brake Assemblies

Updated 08/12/2015 | Published 08/11/2015

Products Featured in This Question

Dexter Electric Trailer Brake Assembly - 10" - Right Hand - 3,500 lbs

(302)

$83.92

10 Gauge Wire - Blue Primary - Per Foot

(107)

$1.65

Question:

I have been reading some others posts but i cant seem to find what I am looking for. I just put on all new trailer breaks all the way around. Backing plate and all. But I still have very weak brakes. They are 12 in brakes on 6k axles. Now when I measure my trailer connector I am only showing 10 volts when I slide my controller and it turned all the way up. Also when I measure on my trailer side of the connection I get an even less 8 volts. Where is my problem coming from. I am losing power the further back I go. Thanks

asked by: Tyler

Expert Reply:

Its not uncommon for there to be slight voltage drop off over a certain distance but with the brake controller set to the maximum you should still be getting 12 volts at the brake magnets.

We need to determine if the low voltage is coming from the controller or somewhere down stream. What you will do is sever the brake controller blue wire several inched back from the controller. Then use your meter to test for voltage on the end of the blue wire coming from the controller while applying the manual override on full.

You should be getting 12 to 14 volts at maximum output. If you are getting less, fluctuations, or nothing then there is something wrong with the controller and it will need to be replaced.

If everything checks out fine at the controller then reconnect the blue wire. Next make sure the vehicle and trailer side connectors are clean and free of corrosion inside and out. On the vehicle, inspect the wiring as far as you can and fix any damaged areas.

On the trailer make sure no wires are pinched or damage and that the grounds are attached to clean and corrosion free bare metal surfaces. If you still get low voltage at the vehicle connector then there must be a wiring issue somewhere that you can't get to.

You could bypass the brake output wire by severing the brake controller blue wire and attaching a different wire, # 10-1-1 (sold by the foot) and routing it back to the trailer connector manually. If you do this be sure to avoid areas that may pinch or burn the wire.

expert reply by: Michael H