Rear Drive Axle Description and Operation
The rear differential assembly in this vehicle consists of an aluminium housing which contains a electric clutch/coupler and a differential. The differential fluid is only contained in the differential housing portion.
The clutch and clutch housing are serviced as an assembly. The fluid level range for proper rear differential assembly operation is 500 ml. New service replacement units will be shipped dry (without fluid). Fill new units with 500 ml of GL Synthetic fluid.
The rear drive axle system operates as follows:
| • | System distributes torque evenly between the 2 rear wheels. |
| • | The system distributes torque to the rear wheels to enhance traction and improve vehicle handling performance. |
| • | The rear differential clutch control assembly contains a main clutch, pilot clutch, electromagnetic coil, rear wheel shaft, main cam, pilot cam. |
| • | The rear differential clutch control module operates by utilising a clutch pack for transferring torque. The engagement mechanism consists of an electromagnetic coil and armature which modulates torque through a pilot clutch and thrust amplification device. |
| • | The rear differential has a micro computer which receives information from the rear differential clutch control module. |
| • | The rear differential clutch control module has an internal temperature sensor, which will maintain consistent and continuous temperature compensation for torque transfer from -40°C to +120°C. When the temperature of the module is determined to be beyond its limits, the rear differential clutch control module will temporarily disable the rear drive system and turn on the AWD Disabled message. When the temperature of the module is back within the limits, the rear differential clutch control module will enable the rear drive system. The temperature sensor and coil are internal to the rear differential, and is replace as an assembly. |
| • | If the vehicle is being driven very aggressively or an unexpected tyre size has been used, the AWD disabled message will be turned on. This should not result in the replacement of rear differential clutch control module. |
| • | The AWD disable message will be turned on if the mini-spare tyre or a very small sized tyre has been installed. This should not result in the replacement of rear differential clutch control module. |
| • | The rear wheel drive clutch coil receives current from the rear differential clutch control module which is used to modulate torque through the use of the engagement mechanism. The greater the current, the greater the torque. The safe current range is between 0.1-3.0 A. If the current range is not within those values DTCs are set and the Service AWD message will appear. The temperature sensor and rear wheel drive clutch coil are internal to the differential and are replaced as an assembly. |
| • | The module uses vehicle speed, steering angle, wheel slip, thermal compensation, and chassis control intervention to determine current. These are serial data messages received from other modules. |
| • | If replacing the rear differential clutch control module, the module needs to be configured for the clutch control calibrations. The connector for the rear wheel drive clutch that connects to the rear differential clutch control module will have a 2 digit code on it. Use that 2 digit code to program the rear differential clutch control module using the scan tool. |
| • | Voltage to the module is between 9-16 V. The module will set a low voltage DTC and a high voltage DTC to indicate voltage value out of range. |
| • | The driver information centre can display a Service All Wheel Drive message. The instrument panel cluster Amber AWD icon will illuminate when the system is disabled. |
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