Troubleshooting HydraStar EOH Trailer Brake Actuator That Runs Without Brake Signal

Updated 10/23/2017 | Published 10/22/2017

Products Featured in This Question

Hydrastar Vented Marine Electric Over Hydraulic Actuator for Drum Brakes - 1,000 psi

(30)

$881.60

Hook Probe Circuit Tester

(65)

$12.94

Question:

Hi. I have a hydrastar hydraulic eletric brakes on boat trailer. When i plug in to car, it makes noise like braking just not as powerful. Even when car is off. Its been hooked up for 2 years. Any ideas? It there is a brake stuck, would that cause it.

asked by: Andrew

Expert Reply:

If the fluid pump on your HydraStar EOH trailer brake actuator such as # HS381-8065 is activating just when it is plugged in to the vehicle (without you pressing the brake pedal or the manual override control on your brake controller) then chances are that you have a short in your wiring. What can happen is that another one of the circuits with 12V power is leaking over to the brake circuit.

Sometimes this issue can be caused by corrosion of the vehicle socket and/or trailer plug. This corrosion may not be visible from the outside of the socket or plug but it can still build up on the inside. Corrosive build-up can contact two adjacent circuits and cause power to reach the brake circuit when it should not. An application of a spray-on electrical contact cleaner can sometimes help.

Another possibility is that the trailer brake controller is damaged, and it is sending out a signal when it should not. This is easy enough to test. If you have a circuit tester like # PTW2993 you can apply it to the controller's blue output wire. Cut this wire a few inches from the back of the controller (leaving enough wire to reconnect it after testing) and apply the tester to the blue wire existing the controller. You should detect a signal on this wire ONLY when you press the brake pedal OR when you press the emergency manual override lever.

If you detect an output from the controller under any other conditions, then the controller is damaged and should be replaced with a new EOH-compatible unit like the Prodigy P2 # 90885 or the P3 # 90195.

expert reply by: Adam R