Antilock Brakes / Traction Control Systems: Description and Operation

ELECTRONIC BRAKE CONTROL MODULE (EBCM)
1. Controls hydraulic pressure to wheeJ cylinders through Valve Block solenoids and main valve.

2. Monitors Brake Switch and wheel speed signals from each wheel speed sensor to determine if and how to modulate a wheel that is beginning to lock up.

3. Controls ANTI-LOCK Indicator.

4. Monitors wheel speed sensors and valves for circuit faults.

VALVE BLOCK
^ Controls hydraulic fluid inlet and outlet when actuated by a 12-volt signal from the Electronic Brake Control Module (EBCM).

WHEEL SPEED SENSORS(4)
^ Send speed information to the Electronic Brake Control Module (EBCM) in the form of AC voltage. Frequency of this signal is proportional to wheel speed.

MAIN VALVE
^ Receives battery voltage signal from the Electronic Brake Control Module (EBCM) during anti-lock braking.

PUMP MOTOR, PRESSURE SWITCH AND PUMP RELAY
^ When Pressure Switch sees low brake fluid pressure at the accumulator, it energizes the Pump Relay which applies power to the Pump Motor. Pump Motor energizes hydraulic accumulator.

BRAKE SWITCH
^ Applies battery voltage to the Electronic Brake Control Module (EBCM) when brake pedal is depressed. Tells module that brakes are applied.

ANTI-LOCK INDICATOR
^ Lights to alert driver of ABS fault and displays ABS trouble codes.

BRAKE INDICATOR
^ Controlled (grounded) by the Pressure Switch, Fluid Level Switch. Ignition Switch. and Park Brake Switch.