LEMON Manuals: Even more car manuals for everyone
Home >> BMW >> 1989 >> 735iL >> Repair and Diagnosis (Single Page) >> Brakes >> Anti-Lock Brakes >> Anti-Lock Brake System - Overview >> Fundamentals of ABS >> ABS Operation >> Normal Braking - "Pressure Build"

Normal Braking - "Pressure Build"

The ABS control module constantly monitors and compares the wheel speed sensor signals. When all four signals are at the same frequency within a small window of tolerance, the ABS system is not active and normal braking takes place.

Fig 1: Identifying Normal Braking - "Pressure Build"
G03403463

The inlet solenoid valves of the hydraulic unit are de-energized. This maintains an open passage from the master cylinder to the brake calipers.

The outlet solenoids are also de-energized. This maintains a closed outlet of the brake circuit back to the master cylinder reservoir.

The inactive scenario is equal to a conventional braking system where the driver applies hydraulic pressure from the brake pedal and the brake calipers react by compressing the brake pads on the rotor.