LR3/Disco 3
An active wheel speed sensor is installed in each wheel hub to provide the ABS module with a rotational speed signal
from each road wheel. The head of each wheel speed sensor is positioned close to a 48 tooth sensor ring on the outer
diameter of the constant velocity joint of the halfshaft. A flying lead connects each sensor to the vehicle wiring.
The wheel speed sensors each have a power supply connection and a signal connection with the ABS module. When the
ignition switch is in position II, the ABS module supplies power to the wheel speed sensors and monitors the return
signals. Any rotation of the halfshafts induces current fluctuations in the return signals which are converted into individual
wheel speeds and the overall vehicle speed by the ABS module.
The ABS module outputs the individual wheel speeds and the vehicle speed on the high speed CAN bus for use by other
systems. The quality of the vehicle speed signal is also broadcast on the high speed CAN bus. If all wheel speed signals
are available to calculate vehicle speed from, the quality of the vehicle speed signal is set to 'data calculated within
specified accuracy'. If one or more wheel speed sensors is faulty, the quality of the vehicle speed signal is set to 'accuracy
outside specification'.
The ABS module monitors the wheel speed sensor circuits for faults. If a fault is detected the ABS module stores a related
fault code and illuminates the appropriate warning indicators, depending on the system functions affected (DSC/ETC,
ABS, EBA/EBD, HDC). A warning chime sounds and, on vehicles with the high line instrument cluster, a related message
is shown in the message center. For additional information, refer to
Instrument Cluster
(413-01 Instrument Cluster)
Since the wheel speed sensors are active devices, a return signal is available when the road wheels are not turning,
which enables the ABS module to check the sensors while the vehicle is stationary. In addition, the direction of travel of
each wheel can be sensed. This information is broadcast on the high sped CAN bus for use by other systems.
YAW RATE AND LATERAL ACCELERATION SENSOR
The yaw rate and lateral acceleration sensor provides the ABS module with inputs of yaw rate and lateral acceleration.
The yaw rate and lateral acceleration sensor is installed under the center console and secured to the transmission tunnel
with two bolts.
When the ignition switch is in position II, the yaw rate and lateral acceleration sensor receives an ignition power feed from
the CJB. The sensor is self diagnosed by the ABS module and can be interrogated using T4. The ABS module
broadcasts the yaw rate and lateral acceleration values, on the high speed CAN bus, for use by other systems.
The ABS module monitors the yaw rate and lateral acceleration sensor for faults. If a fault is detected the ABS module
stores a related fault code and illuminates the DSC warning indicator and, on vehicles with the low line instrument cluster,
the HDC warning indicator. A warning chime sounds and, on vehicles with the high line instrument cluster, a message
advising of an HDC fault is shown in the message center. For additional information, refer to
Instrument Cluster
(413-01
Instrument Cluster)
STEERING ANGLE SENSOR
Item Part Number
Description
1
-
Knuckle assembly
2
-
Sensor ring
3
-
Halfshaft
4
-
Wheel speed sensor
5
-
Screw
