Pump/Motor Assembly

The Bosch III ABS uses an integral pump/motor assembly which is mounted to the transaxle bracket on the left side of the engine compartment. See Figure. The pump/motor assembly takes brake fluid from the hydraulic unit reservoir (through the return hose), pressurizes the fluid and returns it to the accumulator (through the pressure hose). The pump/motor assembly is serviceable as a unit in case of failure. A separate mounting bracket is used to attach the pump/motor assembly to the transaxle bracket. Rubber insulators are also utilized to provide noise isolation.

Pump motor operation is controlled by the pump motor relay, which is mounted on the right hand fender rail behind the coolant reservoir. The relay coil is powered at all times with the ignition on. When pump operation is desired, the pressure monitoring module in the hydraulic unit sensor block provides a ground for the pump motor relay coil.