Final Drive Control Module - Operation
OPERATION
POWER UP/DOWN
The Final Drive Control Module (FDCM) will power up with an OFF/ON transition of the hard wired ignition switch input, or with the presence of active CAN C communications.
The FDCM will power down when the vehicle ignition switch transitions from ON to OFF, or there are no CAN C messages, or there are no system requirements that dictate the controller to remain active
START-UP DIAGNOSTICS
When the FDCM is activated, the internal circuitry will undergo a diagnostic procedure. The controller will examine all inputs and outputs for short circuits to ground, short circuits to battery and open circuits and will also verify proper CPU and memory operation. If a fault is detected, a message will be sent out over the CAN C bus to the Cluster based Electronic Vehicle Information Center (EVIC) indicating that service is recommended.
After passing all diagnostic tests, the controller will receive and process inputs and produce the appropriate outputs. Proper monitoring of the controller inputs and outputs performance will continue.
INPUTS/OUTPUTS
The following are inputs to the FDCM:
- Lateral Accelerometer
- Transfer Case Mode Sensor Signal
- 3 Direct Battery Feeds
- Ignition RUN Sense
- Sensor Grounds
- Module Grounds
- CAN C Bus
The following are outputs of the FDCM:
- 5V Sensor Supply
- Transfer Case Bi-directional Motor Control (A AND B)
TRANSFER CASE MODE SENSOR SIGNAL
The Transfer Case Mode Sensor Signal Input will provide the FDCM feedback about the position of the transfer case. The mode sensor will be a linear analog position sensor with a 1.4K +/- 20% potentiometer and a 1 K +/- 20% resistor that converts the motor shaft position into a multiplexed voltage.
SLIP CONTROL
Slip Control increases torque to the front axle when a relative slip is detected between the front and the rear prop shafts.
Slip Control adjusts according to the vehicle speed and allows a permissible slip.
Utilizes a closed loop strategy for permissible slip and speed of engagement.
STABILITY CONTROL
Stability control modifies the torque request based upon the vehicle dynamics under the over-steer and under-steer conditions.
It monitors the yaw rate and the lateral acceleration to modify the clutch capacity to bring the vehicle back to a more neutral attitude.
Compensates for high load conditions by monitoring the vehicle acceleration and changing the torque capacity.
REGENERATIVE BRAKING STRATEGY
During the event of regenerative braking the software splits the torque indicated by the signal axle in a ratio of 47:53 front and rear respectively.
This torque split is to be modified to achieve optimum efficiency levels during a braking event.
MODES OF OPERATION
Normal Operation
This mode is achieved by the ignition being switched in the RUN position, which powers up the 5V regulator and generates the appropriate RESET for the microprocessor. This mode also includes any required power-up system checks.
Shut Down Mode
This mode is activated when the ignition switch turned to the off position. The FDCM will perform any required Shut Down tasks prior to turning off the 5V regulator.
Limp-In Mode
This mode is entered when the FDCM has detected an error condition that prevents the system from performing its' required task. The FDCM operation will vary depending from modified operation to total system shut down based on the failure that has occurred.