Does Hydrastar EOH Adapter Module for GM Brake Controllers Install On Truck Or Trailer
Updated 08/26/2026 | Published 08/17/2026
Question:
Does this install in the truck or on the fifth wheel?
asked by: Michael A
Expert Reply:
Hey Michael! The Hydrastar Electric Over Hydraulic Actuator Adapter Module for GM Brake Controllers # HYD29ZR will be installed on the trailer side. This is designed to be installed on your brake output circuit between the brake controller and the Hydrastar actuator. See the attached photo.
The module should be ~10" from the actuator. Official installation instructions from Hydrastar are "cut the blue wire approximately 10" from the actuator. Crimp the module inline — wires are labeled for direction. Heat shrink the connections. Arrow on the diode points toward the actuator."
What kind of 5th wheel are you towing?
(click to enlarge)
Greg
8/25/2026
I put mine on the trailer and it works fine.
Robin H.
8/25/2026
Bruce J.
8/25/2026
Hydrastar instructions indicate installing the adapter within 10” of the actuator in the brake controller output conductor. Just cut the blue wire near the actuator and install with the include crimp connectors. Polarity matters. Quick, simple fix.
Robin H.
8/25/2026
Dave K.
8/25/2026
Easy to install in camper near hydrastar unit. Tip is H end goes to hydrastar unit. T goes to truck.
Robin H.
8/26/2026
Product Page this Question was Asked From
Hydrastar Electric Over Hydraulic Actuator Adapter Module for GM Brake Controllers
- Accessories and Parts
- Trailer Brake Controller
- Modules
- Vehicle Specific
- Hydrastar
more information >
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Michael A.
8/24/2026
Thank you for your reply. I am towing a 2023 Montana with a 2026 Chevrolet 3500. Even when I turned the solar off, I still lose brakes.