EPS System Operation
The Electric Power Steering (EPS) Pump has different modes on which it will operate. A list of the modes follows:
- Wake Up Mode - The EPS Pump control module initiates when ignition is in RUN or START positions. This begins startup checks (memory checksums, internal sensors, faults etc.) and starts monitoring the vehicle CAN system.
- Start Mode - The EPS module will start the electric pump motor to provide steering assist once one of the following occurs: Hybrid propulsion system active message is received (vehicle is started), or a vehicle speed message of greater than 3 mph (5 kp/h) is received.
- The EPS Pump will then run until the ignition is turned off regardless of further changes in Hybrid Propulsion System or Vehicle Speed messages. There may be degraded assist during evasive maneuvers when there is no vehicle speed message.
- Sleep Mode - If steering wheel is not moved for 5 seconds with vehicle speed less than 3 mph (5 kp/h) the pump will reduce output flow to 0.5 gpm to minimize current consumption and heat buildup. Any steering wheel movement will return pump to normal operation.
- Endlock Mode
- If the steering wheel is held in lock (wheels to wheel stops) for 1 second or more with vehicle speed less than 12.5 mph (20 kp/h) the pump will reduce output flow to 0.5 gpm to minimize current consumption and heat buildup. NOTE: Holding the steering wheel in the lock position for more than 3 seconds can damage the EPS system.
- Shut Down Mode
- At shutdown (loss of ignition signal to the module), the pump will:
- Write any stored DTCs to EEPROM.
- Shut down.