Hydraulic Control Unit
WARNING: This page is about a different car, the 2004 Mercury Marauder, 2004 Mercury Grand Marquis, and 2004 Ford Crown Victoria. However, it is still accessible from the selected car via links, so may be relevant.
The hydraulic control unit is located in the engine compartment on a bracket attached to the frame rail. The brake pressure control valve block and pump motor are installed as an assembly. It consists of the following components:
- Brake pressure control valve block
- Pump motor
Operation of the hydraulic control unit is as follows:
- During normal braking, fluid passes through four normally open inlet valves, one to each wheel.
- If the anti-lock brake control module senses a wheel is about to lock, it pulses the appropriate inlet valve which closes that valve. This prevents any more fluid from entering the affected brake.
- The anti-lock brake control module then looks at that wheel again. If it is still decelerating, it opens the normally closed outlet valve which decreases the pressure trapped in the line.