Engine Does Not AutoStop
Engine Does Not AutoStop
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
Typical Scan Tool Data
Circuit/System Description
This vehicle does not use a 12V starter motor to crank the internal combustion engine. A much more powerful 300V motor/generator located within the transmission is utilized to crank the engine. The 300V motor/generator can rotate the engine to operating speed, 800 RPM, within just a few hundred milliseconds. The 300V motor/generator allows near-instant starting of the engine. Once started, engine operation may cycle between Autostop, engine off, and Autostart, engine running, for the duration of the drive trip.
Autostop/Autostart
The Two-Mode Hybrid vehicle does not require internal combustion engine operation at all times. After a successful engine start, the hybrid powertrain control module may turn off the engine, or Autostop, when not required for the current vehicle conditions. The engine will remain off while in Autostop mode, until such time that vehicle conditions require the engine to run. The near-instant starting of the engine from Autostop mode is called Autostart.
Autostop Conditions
Numerous conditions must all be within acceptable limits in order for the hybrid powertrain control module to allow the Autostop hybrid mode. The Typical Scan Tool Data information lists the vehicle conditions required for Autostop operation.
Diagnostic Aids
A chime will sound if the drivers door is opened while in Autostop as a reminder that the engine is not in the OFF mode.
Engine OFF and AUTO STOP modes are indicated on the tachometer display.
When the tachometer needle indicates OFF, the engine is not running and will remain Off until the ignition key is placed in the Crank position or a remote vehicle start request is received from the keyless entry transmitter. Autostop is not allowed with a remote vehicle start.
When the tachometer needle indicates AUTO STOP, the engine is not running but may Autostart at any time without notice.
Reference Information
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Circuit/System Verification
1. Hood closed, start the engine with the ignition key and allow to idle.
2. Monitor engine operation and the tachometer display for 5 minutes.
3. The vehicle should enter the Autostop hybrid mode.
• If the vehicle operates in the Autostop hybrid mode, the system is operating normally.
• If the vehicle cycles rapidly in and out of the Autostop hybrid mode, test the auxiliary transmission fluid pump pressure. Refer to Line Pressure Check Line Pressure Check.
• If the vehicle does not operate in the Autostop hybrid mode, continue to Circuit/System Testing.
Circuit/System Testing
1. Verify no hybrid powertrain control module or ECM DTCs are set. Repair any hybrid powertrain control module or ECM DTCs prior to performing this diagnostic procedure.
2. Engine at idle, observe the hybrid powertrain control module Autostop Inhibit Reasons scan tool parameter.
3. Compare the parameter display to the Typical Scan Tool Data information.
4. Identify which Autostop inhibit conditions have prohibited Autostop operation. An Inhibit condition will display YES on the scan tool.
5. Determine if the Autostop inhibit conditions are the result of normal operating conditions or the result of a fault condition.
• Repair the conditions that are the result of a fault condition. For example, a hood switch that indicates hood status as open when the hood is actually closed.
• Advise the vehicle operator of the normal operating and environmental conditions that will inhibit Autostop. For example, advise that Autostop is disabled when hybrid Battery Pack temperature is less than 10°C (50°F).