Engine Stop Start System: Notes
DESCRIPTION
The following list indicates some of the components involved in the Engine Stop Start (ESS) system:
| 1. | Refer to GENERATOR . |
| 2. | Refer to STARTER MOTOR . |
| 3. | Refer to TRANSMISSION CONTROL MODULE (TCM) - Automatic Transmissions (ATX) only. |
| 4. | Refer to INSTRUMENT PANEL CLUSTER (IPC) . |
| 5. | Refer to START/STOP OFF SWITCH - Located in the lower steering column cover. |
| 6. | Refer to BODY CONTROL MODULE (BCM) . |
| 7. | Refer to ANTI-LOCK BRAKE SYSTEM (ABS) MODULE . |
| 8. | Refer to INTELLIGENT BATTERY SENSOR (IBS) . |
| 9. | Refer to DUAL BATTERY SYSTEM AND RELAYS (Primary and Auxiliary Batteries). |
| 10. | Refer to POWERTRAIN CONTROL MODULE (PCM) . |
| - | Refer to STARTER MOTOR RELAY - Located within the main Power Distribution Center (PDC). |
| - | Refer to POTENTIAL ESS SYSTEM INHIBITORS . |
The ESS system automatically stops and starts the engine when certain conditions are met to improve fuel economy and lower Carbon Dioxide (CO2) emissions. The START/STOP Off switch is integral to the ICS.
The Battery, Starting and Charging systems operate in conjunction with one another, and must be tested as a complete system. For correct operation of starting/charging systems, all components used in these three systems must perform within specifications. When attempting to diagnose any of these systems, it is important that you keep their interdependency in mind.
Certain starting system components and functions of the ESS system are On Board Diagnostics (OBD) II monitored and will produce Diagnostic Trouble Codes (DTC). The use of the diagnostic scan tool is not only recommended, but it is necessary for proper diagnosing of the ESS system and the components or systems that are related to ESS system functions. Review the component and system information listed below in the operation section for diagnostic information. Otherwise, review the wiring information and section the appropriate diagnostics service information.
OPERATION
The vehicles first engine crank event is managed by the driver acting on the ignition state and requesting an engine crank request. When this request occurs, the BCM cranking relay is opened and the PCM cranking relay is closed. When the engine is ON and the engine cranking phase has ended, the PCM cranking relay will now be opened and the BCM cranking relay will now be closed. All of the next automatic ESS cranking events managed in the same Key ON ignition cycle are performed maintaining the BCM cranking relay closed and setting closed the PCM cranking relay. Each time an ESS cranking event occurs which causes the engine to come on again, the PCM cranking relay is opened.
For ATX equipped vehicles, the PCM sends a signal to TCM to indicate it is ready for an ESS event, then TCM responds it is ready for ESS and enters a hydraulic neutral state while in an Autostop event and stays in hydraulic neutral while Autocranking to avoid vehicle movement during engine cranking.
For MTX equipped vehicles, the PCM will initiate the ESS start event with a short press of the clutch pedal when the MTX is in neutral. The PCM will allow an ESS autostart event to occur while in a drive engaged gear if the clutch pedal travel goes past the interlock position. Otherwise the PCM will trigger an IPC display message to alert the driver to either press the clutch in or shift the transmission into neutral.