DTC 11

REPLENISHING VALVE OPERATION

The replenishing the valve is included in the valve block assembly and, when engaged, directs pressurized brake fluid from the booster servo (hydraulic) circuit to the master cylinder chambers. This feature serves to prevent excessive pedal travel when anti-lock mode is engaged and during hard braking without anti-lock control. The replenishing valve also prevents a low or soft pedal if air is present in the hydraulic System.

Attached to the replenishing valve is a feedback switch (Sw) which is closed to ground when the valve is not activated. The feedback switch opens when the replenishing valve is engaged.

CIRCUIT OPERATION

The replenishing valve circuit receives power through the valve relay. The valve relay, which is included as part of the sensor block assembly, is engaged at key-on and remains engaged throughout the ignition cycle. The replenishing valve line (at the EBCM) should have battery voltage present at all times.

The replenishing valve feedback line is held at 5 V by the EBCM. When the replenishing valve is not engaged, the feedback line is grounded (0 volts) by the feedback switch (Sw).

The replenishing valve is engaged under two conditions:

1. When booster piston travel switch S2B opens during normal braking, indicating particularly hard braking without anti-lock control. Booster piston travel switches are discussed under "ABS Codes 13, 14 & 15" operation.

2. Whenever anti-lock mode is entered.

The EBCM engages the replenishing valve by grounding pin 30 at the controller. When the replenishing valve is engaged, the feedback switch (Sw) opens and the feedback switch line voltage is raised to 5 V.

FAILURE CONDITIONS

ABS Code 11 will set anytime that the commanded replenishing valve position and the valve position indicated by the feedback line do not agree. With the valve not engaged, the feedback line (pin 33) should be at ground. With the valve engaged, the feedback line should be at 5 V.