Troubleshooting EOH Brakes With Hydrastar Actuator Not Working With 2024 Ford F-450

Updated 11/13/2025 | Published 05/22/2025

Question:

I have a hydraster bracke actuator in my diamond c trailer, when I hook up my harness to my new truck, it doesn’t allow the brakes to activate but everything else on the trailer works. Can anyone here help me with this issue? Do I need to purchase an adapter to help it communicate with the truck?

asked by: Shane E

Expert Reply:

Hi Shane; sometimes the adapter module # HBA-CAM is needed to help the brakes function properly. However, before you go this route I would check out the brake controller. More often than not you need to switch to electric over hydraulic mode for the brakes to work with an actuator like the Hydrastar. If I had to guess, the brake controller is not set to EOH which is why it is not working properly.

expert reply by: Robin H

Adapter Module
(click to enlarge)

Shane E.

5/25/2025

I have checked the settings it is EOH. So that part is compatible with a 2024 f450?

Robin H.

5/25/2025

@ShaneE yes, it is compatible with any vehicle/setup.

Shane

6/4/2025

@RobinH hey so I bought that part that was suggested and my brake actuator still does not work with my 2024 f450, I’ve taken it to the dealer and they say there’s no issues with the truck so am I missing something? Does that part 100% work with this truck?

Robin H.

6/4/2025

@Shane it is not a truck dependent part. What it does is put enough load on the brake output circuit for the brake controller to think a trailer is connected. If you were to install this with something like the Prodigy P3 # 90195, which we know will work without it, it will not impact functionality of the brake controller and the Hydrastar actuator will still work as intended. It works with any brake controller on any vehicle. Do you get any errors when you're hooked up to the trailer? I think the best thing at this point is to run through everything with a circuit tester to try to narrow down the problem. I wouldn't uninstall the HBA-CAM at this point either since it can only help assuming it is properly installed. Since everything on the vehicle is theoretically working test the brake output on the trailer side while using the manual override to make sure power is getting through to the actuator and go from there. I doubt it is the trailer connector since you said everything else functions but it is still possible. Can you tell if the brakes are engaging at all while using the manual override? Is the Hydrastar actuator making a humming or buzzing sound indicating it is working?

Don

11/13/2025

@RobinH I have a 2023 F350 in the shop right now and they are working on the problem. I also have a 2001 f350 and it works with the Hydrastar actuator but the brake controller is a Tekonsha. I have the Hydrastar cam installed from the trailer manufacturer. The 2023 f350 has been hooked up to other Hydrastar actuators and it does not work with them either. My son has a 2024 f350 and it will not get the Hydrastar actuator to work as well. All we get is a click sound from the actuator when engaging the brakes. Voltage on the blue wire is 8v when the trailer gain is set to 6. The voltage on the red wire is 0. I also have a couple of other trailers that use electric brakes and they work with the 2023 as they should . I hired a technician to take the dash apart to get to the back of the factory brake controller. I told him to unplug it and to install an aftermarket controller that I bought from etrailer. He reported that there was nothing to unplug or to splice into as the factory brake controller has a data cable coming out of it that goes to a module. He buttoned it back up. The evidence so far leads me to believe that this is a software issue that is specific to certain trim and option packages that ford produces.

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