How To Troubleshoot Surge Brake Actuator On a Boat Trailer

Updated 01/22/2025 | Published 01/20/2025

Question:

Hi I have a Dexter system on my boat trailer. It does not work with my 2018 GMC seirra. I have a feeling it is shot but some say they will not work with GMC, Can you clarify? Maybe give me some things to troubleshoot to see if the unit is good? Regards,

asked by: Russell W

Expert Reply:

Hey Russell, I'm assuming you're talking about a surge actuator. So to test to see it's bad or not, or if it's your truck, you can jack up one side of the trailer and spin the wheel while someone manually activates the surge actuator on the coupler; if the wheel stops spinning, the actuator is likely working properly.

You can also visually check for any leaks or breaks as that could also be a reason it's not working.

Let me know in the comments if you have any questions, and I'd be happy to help!

expert reply by: Bryce D

Russell

1/20/2025

Hey Bryce, Sorry I was far from clear. I have a electric over hydraulic braking system on my trailer. Ive read that they wont play nice with GM built in controller, BUT i also think the unit is shot. 2 questions 1- How do I test the unit? When you say activate the surge actuator, you are referring to the in dash controller correct? Ive done this already and nothing happens. When I plug harness into my truck the Dexter pump runs constantly (even when the truck is turned off) Seems like a sign that things are amiss. 2-If this system does not play nice with GM trucks, can you recommend one that does work? Russ

Bryce D.

1/20/2025

@Russell Hey Russell, I think we were on different pages. I believe you're referring to the OEM brake controller in which you can test by isolating the blue brake output wire, then apply the manual slide while checking for power on the wire using a circuit tester; if there is power present only when the manual slide is activated, the controller is good, otherwise, you'll want to check for issues with the wiring or the controller itself. You should also make sure to verify there is power on the black wire (constant) and that the red wire (only when the brake pedal is pressed). If it turns out you do need a new brake controller, then I'd suggest Tekonsha Prodigy P3 # TK57HR.

Russell

1/20/2025

The controller on the truck is good. I have 5 trailers I use with it and all brakes work. The gizmo on my boat trailer is different. (all my other trailers have electric brakes, the boat has electric of Hydraulic EOH) The EOH does not work.

Bryce D.

1/22/2025

@Russell Then the issue is likely either with the actuator itself or with the wiring on your trailer. I recommend first checking voltage, and making sure the power is reaching the actuator. To check the actuator you can disconnect it, and hook it up to a battery to see if the motor functions properly. I'd also recommend inspecting all the wiring for damage or corrosion.