Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions)provides an overview of each diagnostic category.
DTC Descriptor
DTC P2797
- Auxiliary Transmission Fluid Pump Performance
Diagnostic Fault Information
Typical Scan Tool Data
Circuit/System Description
The auxiliary transmission fluid pump (ATFP) system supplies the transmission with hydraulic pressure when the vehicle is operating in the
internal combustion engine (ICE) Autostop hybrid mode. The ATFP system consists of an ATFP control module that operates an electric, 12V 3
phase alternating current (ac), motor-driven pump. Two pulse width modulated (PWM) status circuits connect the ATFP control module to the
hybrid powertrain control module (HPCM). The transmission auxiliary oil pump control circuit delivers the HPCM commanded pump speed to the
ATFP control module. The transmission auxiliary oil pump diagnostic circuit supplies the HPCM with the actual pump speed and also with the
operating status of the ATFP control module. The HPCM monitors these circuits for fault conditions.
The ATFP control module inverts 12V direct current (dc) into 12V, 3 phase ac current to operate the pump motor.
The ATFP control module monitors the status of the ATFP motor/pump as well as its own internal circuitry. The ATFP control module does not
store its own diagnostic status. Current ignition cycle diagnostic status is reported to the HPCM over the transmission auxiliary oil pump diagnostic
circuit. The diagnostic status within the ATFP control module is reset at every ignition-off cycle.
Conditions for Running the DTC
* Ignition voltage is 8-18 volts.
* The auxiliary transmission fluid pump is commanded ON.
Conditions for Setting the DTC
The HPCM observes the difference between actual and commanded ATFP pump speed is greater than 500 RPM for 4 out of 4.125 seconds.
Action Taken When the DTC Sets
* DTC P2797 is a Type B DTC.
* The drive motor generator power inverter control module (PIM) disables the Autostop hybrid mode.
Conditions for Clearing the DTC
DTC P2797 is a Type B DTC.
