Functional Description - Electric Power Steering (EPS) System
The BCM receives the Steering Angle Sensor (SAS) data from the Electric Power Steering (EPS) module in the steering gear and broadcasts the data on the Controller Area Network - Flex-Data (CAN-FD) data bus for BCM calculations. The BCM gates all LIN data from the EPS module.
The main functions of the EPS Module are to:
- Monitor the steering system for proper operation
- Detect wheel locking or wheel slipping tendencies by monitoring the speed of all four wheels of the vehicle
- Control fluid modulation while the system is in a slip mitigation event
- Store diagnostic information
- Provide communication to the diagnostic scan tool while in diagnostic mode
- Provide vehicle speed information, by monitoring the wheel speed sensors, to all modules on the CAN bus
- Control the EPS system
- Monitor steering force in the hydraulic system by comparing the EPS Steering Sensor (Searing Gear) data and the Steering Column Control Module (SCCM) sensor data in order to determine if the brake lights need to be activated (both pressure sensors are internal to the EBB)
The EPS constantly monitors the steering system for proper operation. If the EPS detects a fault, it will illuminate a warning indicator lamp and disable some functions. The base braking system will remain operational.
The EPS continuously monitors the speed of each wheel through the signals generated by the wheel speed sensors to determine if any wheel is beginning to lock. When a wheel locking tendency is detected, the EPS commands the coils to actuate. The coils then open and close the valves that modulate brake fluid pressure in some or all of the hydraulic circuits. The EPS continues to control pressure in individual hydraulic circuits until a locking tendency is no longer present. The EPS contains a self-diagnostic program that monitors the steering system for system faults. When a fault is detected, a warning indicator lamp is turned on and a Diagnostic Trouble Code (DTC) fault is then stored in a diagnostic program memory. A latched fault will disable certain system functionality for the current ignition cycle. An unlatched fault will disable certain system functionality until the fault condition disappears. These DTCs will remain in the EPS memory even after the ignition has been turned OFF. The DTCs can be read and cleared from the EPS memory by a technician using a diagnostic scan tool. If not cleared with a diagnostic scan tool, the fault occurrence and DTC will be automatically cleared from the EPS memory after the identical fault has not been seen during the next 3, 500 miles. Drive-off may be required for the amber MIL indicator lamp to go out on the next ignition cycle.
The EPS works in conjunction with multiple subsystems including, BSCM and Instrument Cluster. All of these systems work together to enhance vehicle stability and control in various driving conditions.
The EPS receives acceleration and parking maneuvers using system calculations.
The EPS is powered by two 80 amp fuses in the Power Distribution Center (PDC).
The main functions of the Steering Column are to:
- Monitor the power steering system for proper operation
- Control fluid modulation while the system is in a slip mitigation event
- Store diagnostic information
- Provide communication to the diagnostic scan tool while in diagnostic mode
- Illuminate the Malfunction Indicator Lamp (MIL)
- Illuminate the MIL function lamp when a vehicle dynamic event is occurring during the steering system
- Provide vehicle speed information, by monitoring the wheel speed sensors, to all modules on the CAN bus
The EPS constantly monitors the steering system for proper operation. If the EPS detects a fault, it will illuminate a warning indicator lamp and disable partial functions.
The EPS continuously monitors the speed of each wheel through the signals generated by the wheel speed sensors to determine if any wheel is beginning to lock. When a wheel locking tendency is detected, the EPS commands the coils to actuate. The coils then open and close the valves that modulate brake fluid pressure in some or all of the hydraulic circuits. The EPS continues to control pressure in individual hydraulic circuits until a locking tendency is no longer present. The EPS contains a self-diagnostic program that monitors the antilock brake system for system faults. When a fault is detected, a warning indicator lamp is turned on and a Diagnostic Trouble Code (DTC) fault is then stored in a diagnostic program memory. A latched fault will disable certain system functionality for the current ignition cycle. An unlatched fault will disable certain system functionality until the fault condition disappears. These DTCs will remain in the EPS memory even after the ignition has been turned OFF. The DTCs can be read and cleared from the EPS memory by a technician using a diagnostic scan tool. If not cleared with a diagnostic scan tool, the fault occurrence and DTC will be automatically cleared from the EPS memory after the identical fault has not been seen during the next 3, 500 miles. Drive-off may be required for the amber ABS warning indicator lamp to go out on the next ignition cycle.
The EPS works in conjunction with multiple subsystems including, Drag Torque Control, EBD, ESC, ESC, Rain Brake Support, Ready Alert Braking, TCS, TSC and YMC. All of these systems work together to enhance vehicle steering and control in various driving conditions.
The EPS is powered by two 50 amp fuses in the Power Distribution Center (PDC). The EPS receives an ignition RUN/START feed from a 10 amp fuse in the PDC.
The main functions of the Steering Gear are to:
- Monitor the steering system for proper operation
- Control fluid modulation while the system is in a assist steering event
- Store steering diagnostic information through the Malfunction Indicator Light (MIL) message
- Provide communication to the diagnostic scan tool while in diagnostic mode
The EPS constantly monitors the steering system for proper operation. If the EPS detects a fault, it will illuminate a Malfunction Indicator Lamp (MIL) and disable some steering assist functions. The manual steering system will remain operational.
The EPS continuously monitors the speed of each wheel through the signals generated by the wheel speed sensors to determine if any wheel is beginning to lock. When a wheel locking tendency is detected, the EPS commands the coils to actuate. The coils then open and close the valves that modulate brake fluid pressure in some or all of the hydraulic circuits. The EPS continues to control pressure in individual hydraulic circuits until a locking tendency is no longer present. The EPS contains a self-diagnostic program that monitors the steering system for faults. When a fault is detected, a warning indicator lamp is turned on and a Diagnostic Trouble Code (DTC) fault is then stored in a diagnostic program memory. A latched fault will disable certain system functionality for the current ignition cycle. An unlatched fault will disable certain system functionality until the fault condition disappears. These DTCs will remain in the EPS memory even after the ignition has been turned OFF. The DTCs can be read and cleared from the EPS memory by a technician using a diagnostic scan tool. If not cleared with a diagnostic scan tool, the fault occurrence and DTC will be automatically cleared from the EPS memory after the identical fault has not been seen during the next 3, 500 miles. Drive-off may be required for the amber ABS warning indicator lamp to go out on the next ignition cycle.
The EPS works in conjunction with multiple subsystems including, APB, BAS, Drag Torque Control, EBD, EPB, ERM, ESC, HDC, HSA, ORA ESC, Rain Brake Support, Ready Alert Braking, TCS, TSC and YMC. All of these systems work together to enhance vehicle stability and control in various driving conditions.
The EPS receives acceleration and yaw data from the ORC for use in making ESC system calculations.
The EPS is powered by two 50 amp fuses in the Power Distribution Center (PDC). The EPS receives an ignition RUN/START feed from a 10 amp fuse in the PDC.