Replenishing Valve Operation

Early Production ABS Operation

The replenishing valve is a two piston valve which is controlled by the Anti-lock Brake Control Module (ABM). This valve is opened during anti-lock braking and hard braking without anti-lock operation. When the replenishing valve is engaged, pressurized fluid from the booster servo circuit is redirected into the master cylinder to prevent excessive pedal travel.

Due to the high fluid pressure present when the replenishing valve is activated and slight pressure differences between the servo circuit and the master cylinder, a slight "clunk" may be felt and heard when the replenishing valve is activated. This is particularly evident during the Built-In Test Equipment (BITE) portion of the system self test, as the replenishing valve function is checked by the ABCM.

A switch, designated SW, is opened by the replenishing valve upon activation. If switch SW fails to open upon activation of the replenishing valve, the ABCM detects a fault and records a fault code.