Operation

(Continued)

The warning light is powered via the ignition switch (+15VDC) and is off only when battery voltage reaches pin (6) on the instrument panel (2) via the ABS ECU (1).

When the ignition switch is at MAR, the ABS system warning light comes on. It goes out after approximately two seconds if no faults are found. If on the other hand a fault is found, the red LED stays on and the ABS system is deactivated leaving the traditional braking system enabled.

The warning light can come on and the ABS may be cut out if the battery is not sufficiently charged, e.g. when driving in towns with all the electrical devices on.

OPERATION

Home position

Each branch of the Bosch 5.3 ABS hydraulic circuit presents two two-way solenoid valves controlled by the ECU (1).

When deactivated, the charging solenoid valve (9) is open thus allowing the passage of fluid to the brake calliper.

Pressure is kept by closing this valve, i.e. powering it electrically.

(Cont.d)