Automobile & Light Truck Certification Test A5 BrakesAnti-lock Brake System (ABS) Diagnosis and RepairMedium
A vehicle equipped with Electronic Stability Control (ESC) is experiencing an intermittent ABS warning light and a C1223 fault code, indicating a 'Yaw Rate Sensor Circuit Malfunction'. Which of the following is the PRIMARY function of the yaw rate sensor in an ESC system?
- ATo measure the vehicle's lateral acceleration
- BTo monitor the steering wheel position and angle
- CTo determine individual wheel speeds for brake control
- DTo detect the vehicle's rotational movement around its vertical axis
Show answer & explanationAnswer & explanation
Correct answer: D. To detect the vehicle's rotational movement around its vertical axis
The yaw rate sensor specifically measures the vehicle's angular velocity around its vertical axis, informing the ESC system about the vehicle's rotation and helping to detect oversteer or understeer conditions.
Why the other options are wrong
- A. Lateral acceleration is typically measured by a separate G-sensor, though sometimes integrated.
- B. Steering wheel position is monitored by the steering angle sensor, a different component.
- C. Individual wheel speeds are measured by the wheel speed sensors, not the yaw rate sensor.
Yaw Rate Sensor
A sensor that measures the vehicle's angular velocity around its vertical axis, indicating how fast the vehicle is rotating.
- Crucial input for Electronic Stability Control (ESC).
- Detects oversteer and understeer conditions.
- Often located near the vehicle's center of gravity.
Memory trick: YAWN! The car spins around me like a sleepy top.