System Evolution
What was the first generation of electronic brake control systems called?
Antilock Brake System (ABS)
What does ABS stand for?
Antilock Braking System
Name three main ABS components.
ABS master cylinder, power booster, EBCM
What does TCS stand for?
Traction Control System
What does ESC stand for?
Electronic Stability Control
What does ABS prevent during braking?
Wheel lockup
How many times per second can ABS cycle the brakes?
About 16 times per second
What does the brake switch signal to the EBCM?
When the driver applies the brakes
What additional components are added to ABS for TCS?
High-pressure pump, accumulator, boost valves
Name two sensors unique to ESC systems.
Steering angle sensor, yaw sensor (also roll-rate sensor)
Which system was developed after ABS to help maintain traction during acceleration?
Traction Control System (TCS)
What mode isolates the master cylinder from the brake circuit?
Hold mode
List the three types of wheel speed sensors.
Variable reluctance, magneto-resistive, Hall effect
How can TCS reduce engine power? Name two methods.
Closing throttle plate, shutting down fuel injectors (also reducing timing or upshifting)
What does the yaw sensor measure?
Directional rotation of the vehicle on its vertical axis
What system helps prevent rollovers and loss of control?
Electronic Stability Control (ESC)
Maximum braking traction occurs when wheels rotate what percent slower than vehicle speed?
10–20% slower
Which wheel speed sensor type produces a digital square wave signal?
Hall effect sensor
Where does hydraulic pressure for TCS originate?
From a brake fluid pump and accumulator
How many wheels can ESC apply brakes to for stability?
Up to three wheels
Name two advanced features added to ESC systems.
Hill assist, trailer sway control (others include panic stop assist, hill descent control)
What causes the pulsation felt in the brake pedal during ABS activation?
Rapid hydraulic pulsations from solenoid valves
What does the EBCM use to make brake control decisions?
Sensor input data compared to stored data maps
What dashboard feature allows temporary TCS deactivation?
TCS function switch
Name two advanced ESC functions beyond basic stability control.
Hill descent control, accident avoidance braking