Rear Differential Control Module (RDCM)

The RDCM controls operation of the electric rear differential.

Vehicles up to 14MY  : The RDCM is attached to a bracket located on the right side of the luggage compartment, forward of the tail lamp assembly, behind the trim.

Vehicles from 14MY  : The RDCM is attached to a bracket located on the right side of the luggage compartment, above the right wheel arch on saloon models. On Sportbrake models the RDCM is located on right side of the luggage compartment, on a bracket behind the right rear seat backrest.

The RDCM receives three battery feeds from the AJB (auxiliary junction box) and an ignition feed from the CJB (central junction box). A connection with the high speed CAN bus allows the RDCM to communicate with other systems on the vehicle.

A certain amount of differential slip is required to allow the vehicle to turn corners and to remain stable under control of the ABS. The ISCM monitors the driver's demands through primary vehicle controls and automatically sets the slip torque in the differential. The system is completely automatic and does not require any special driver input.

The differential strategy in the ISCM includes:

• A pre-loading function, increasing locking torque with increased driving torque.
• A slip controller to decrease locking torque for optimum comfort, for example, parking.

The ISCM memorizes the position of the differential locking motor when the ignition is switched off.

CAN bus messages used by the ISCM include wheel speed, steering angle, automatic transmission speed, temperature information, car configuration, axle ratios and mode inputs.

The ISCM also sends messages via the CAN bus to tell other control modules on the network the status of the electric rear differential. The clutch torque and default mode status are some of the main signals sent out by the ISCM

If the RDCM or ISCM are replaced, a Jaguar approved diagnostic system must be connected to the vehicle and the differential self-calibration procedure must be performed. This procedure must also be performed if the differential locking motor or electric rear differential is replaced.

If a fault occurs with the electric rear differential, the ISCM, the RDCM, or one of the required input signals, the ISCM records an error code and displays a warning in the message center.

The following messages can be displayed: