Monitoring And Fault Detection

Electrical faults monitoring:  The wiring to the EMF control module including the actuator motor are monitored for breaks or shorts to B+ and ground.

Hydraulic interface monitoring:  The DCS checks the plausibility of the deceleration request by the parking brake during Dynamic Braking and the hydraulic Hold Function. If the request and feedback do not agree within a defined time (5 seconds), the corresponding shut down stage is assumed and a fault code will be stored.

Input signals monitoring:  In the event of a faulty input signal, the entire system is shut down with a Check Control error message and a stored fault code.

Parking brake push button monitoring:  The push button signals are continually monitored (hardwired to the EMF control module). In the event of a push button plausibility fault, the entire parking brake system is shut down and the "Parking Brake Push Button Defective" fault code is stored. The DSC control module also checks the plausibility of the parking brake push button signals that are transmitted via the CAN Bus (from the EMF control module). If faulty, the "Parking Brake Push Button Signals via CAN Implausible" fault code is stored and partial shut down is carried out (Dynamic Braking is not possible).

Speed signals monitoring:  Total shut down of the parking brake system will occur with the loss of all 3 speed inputs.

• The direct digital wheel speed signal (separate hard wire backup, front left) is continually checked for the plausibility of the signal edge change.
• The plausibility of the reference speed signal from the DSC over the PT-CAN Bus and the direct digital wheel speed signal is continually and mutually checked.
• The reference speed signal from the DSC is compared with the automatic transmission output speed.

  Fault codes:

• Direct wheel speed signal implausible or faulted
• DSC speeds implausible or no message
• EGS automatic transmission output speed implausible or no message

Hall sensors monitoring:  The plausibility of the actuating motor Hall sensors is continually checked. When there are deviations that are out of tolerance, partial shut down (only Dynamic Braking available) is implemented and the "Parking Brake Actuating Unit Defective, Plausibility of Hall Sensors" fault code will be set.

In addition, the plausibility of the position is checked during the actuating motor operation. When the Hall sensor signal is not received, the parking brake system is shut down and a fault code will be set.

EMF actuating unit monitoring:  After the ignition is switched on and a fault is present, it will be detected before a required parking brake function is active.