What Would Cause Trailer Brakes to Lock Up When Trailer Wiring is Connected

Published 06/05/2019

Products Featured in This Question

Kodiak Disc Brake Kit - 12" Hub/Rotor - 6 on 5-1/2 - Dacromet and Stainless - 6,000 lbs

(7)

$715.30

Hook Probe Circuit Tester

(72)

$13.41

Question:

what could make these brakes stick when you plug them up, all lights work fine and when I unplugged them the trailer rolled a little moving truck and trailer this is 2002 car hauler 16

asked by: Rick

Expert Reply:

Sounds like there's a short between the 12 volt accessory circuit which is hot all the time and the brake output circuit which activates the trailer brakes when there is voltage on the circuit. Test the voltage of your 7-way on your tow vehicle with a circuit tester like part # PTW2993 on the pin in the 5:00 position. This should only have power on it when the brakes are applied. If there is voltage here the short is on the vehicle side and most likely behind the connector.

If there isn't voltage here the issue is on the trailer side and will need to be found there. Look for cut or exposed wire and fix as needed.

expert reply by: Jameson C