Chassis / YRS

YAW RATE / LATERAL ACCELERATION SENSOR

Measures vehicle rotation and lateral acceleration for stability control.

SENSOR GUIDE27/86

Correct theory and operation

HOW IT
WORKS.

Understand the sensing method, circuit and controller strategy before interpreting data or replacing the component.

01

Measured condition

Measures vehicle rotation and lateral acceleration for stability control.

02

Signal type

Digital networked sensor. Internal electronics condition the sensing element and transmit calculated data through a dedicated digital line or vehicle network.

03

Controller use

The receiving controller checks range, rationality and rate of change against related inputs before setting a fault or substituting a value.

04

Installation matters

Mounting, target condition, air gap, contamination, temperature, shielding or calibration may affect the result even when the circuit is intact.

Common mistakes

AVOID THE
FALSE CLUE.

Interpreting the recorded data

Normal data pattern

A recorded data trend should change plausibly with the actual operating condition, at the update rate supported by the module and scan tool. Compare related inputs and verify the physical condition independently.

Fault indications

Frozen, discontinuous or implausible data may reflect a sensor or system issue, communication loss, scan-tool filtering or a slow sample rate. A scan-data graph is not a raw electrical waveform; use the specified direct measurement if finer timing is needed.

COMPLETE TEST SEQUENCE

  1. Perform a complete module scan before disconnecting anything.
  2. Verify powers, grounds, wake-up and communication.
  3. Compare the sensor PID with related physical measurements.
  4. Follow calibration, initialization and replacement procedures.
  5. Repeat the original operating condition and confirm the repair.
DO NOT CONDEMN THE SENSOR

Prove its supply, ground, signal path, physical input and calibration before replacement. Vehicle-specific specifications always win.

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Diagnostic details

Purpose

Electronic stability control compares actual vehicle motion with driver intent. Yaw rate is one of the primary measurements used to determine actual vehicle rotation.

Scan tool data

  • Longitudinal acceleration
  • Steering angle
  • Stability-control status

Failure symptoms

  • Stability-control warning
  • Traction-control warning
  • Unwanted stability intervention
  • Calibration faults

Related DTCs

  • Manufacturer-specific yaw-rate DTCs
  • Plausibility codes
  • Calibration codes
  • Communication codes

Diagnostic tips

  • The vehicle may need to be on level ground during calibration.
  • Compare yaw rate with steering angle and lateral acceleration.
  • Check calibration before replacing the sensor.

Construction & type-specific testing

Identify the installed design before testing. Construction, signal format and redundant channels are separate attributes; use only the procedure for the actual component.

MEMS

Microelectromechanical sensor that detects rotational motion.

Operating principle

  • Microscopic internal structures respond to rotational motion.
  • Electronics convert this movement into yaw-rate data.
  • The assembly may also contain acceleration sensors.

Circuit identification

Usually integrated/networked

Wiring

  • Network communication or dedicated signal circuits

Expected readings

  • With the vehicle stationary, yaw rate should generally be near its calibrated zero value.
  • Data should change logically as the vehicle rotates.

Multimeter testing

  • Direct resistance testing is generally not useful.
  • Verify power and ground.
  • Check network communication.

Oscilloscope setup

  • CAN scope testing may be appropriate for communication faults.
  • Direct internal MEMS waveform testing is generally not practical at the vehicle connector.

Oscilloscope testing

  • Use scan data for sensor output.
  • Use a scope for network diagnosis when communication is suspected.

Waveform interpretation

Yaw-rate information is commonly transmitted digitally over the vehicle network rather than as a simple analog waveform.

Common failures

  • Calibration loss
  • Power or ground fault
  • Communication fault
  • Internal sensor fault

Diagnostic tips

  • Do not interpret a calibration problem as automatic proof of sensor failure.