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Yaw rate sensor, lateral acceleration sensor

Yaw rate sensor, lateral acceleration sensor



The yaw rate sensor comprises a combined micromechanical yaw rate sensor and lateral acceleration sensor. It is located on a bracket on the exhaust pipe tunnel ahead of the gear lever. This location has been chosen as the sensor should be positioned as close as possible to the car's centre of gravity and centre line (X-axis).

Its housing is hermetically sealed and filled with nitrogen to protect the components from being affected by the environment. The sensor is used to measure the physical forces of the yaw rate and the lateral acceleration of the vehicle.

Pin Function In/Out Test reading
1

Reference signal

Out

» 2.6 V

2

Reference signal from ESP control module

In

» 3.2 V, 50 Hz square wave, pulse ratio 50%

4

Angle of rotation

Out

-138°/s - +138°/s

5

Lateral acceleration

Out

0 - 5 V

2.6 V when driving straight ahead.

6

System ground

Ground



Yaw rate sensor


The sensor contains a number of thin plates that have weights and are freely suspended independent of each other. The weights, and thereby the plates, move around their own vertical axis in relation to the movement of the vehicle. When the distance between the plates changes, an electrical signal is generated by the gyro sensor. This signal provides the control module with information about the car's rotation.

Lateral acceleration sensor


The acceleration sensor comprises three capacitor plates. One of these capacitor plates is freely suspended between the two fixed plates. The forces of acceleration that arise when the car moves sideways cause the swinging plate to move. This changes the capacitance and an electrical signal is produced. This signal provides the control module with information about the car's lateral movement.

Diagnostics

The yaw rate sensor monitors its own internal functions via the ESP control module. The electronic unit performs self-diagnosis every 20 milliseconds. A DTC is generated if a faulty or improbable signal is produced by the yaw rate sensor, or if there is an open circuit, short to ground or short to a positive cable. The ESP, TCS and ESP OFF lamps will not come on.

Diagnostic help

Yaw rate sensor

The yaw rate sensor value can be read using the diagnostic tool. The reading should be 0°/s when the car is stationary. A DTC is generated if a faulty or improbable signal is produced by the lateral acceleration sensor, or if there is an open circuit, short to ground or short to a positive cable.

The ESP, TCS and ESP OFF lamps will not come on.

Lateral acceleration sensor

The lateral acceleration sensor value can be read using the diagnostic tool. The reading should be 0°/s2 when the car is stationary.