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HOMESERVICE MANUALSCHEVROLET2008CHEVY EXPRESS G2500, VAN CARGO, 6.6 6REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 1534 (HYBRID ENGINE CONTROL SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESDTC P2797CIRCUIT/SYSTEM DESCRIPTION
2008 Chevrolet Chevy Express G2500, Van Cargo, 6.6 6

Circuit/System Description

2008 Chevrolet Chevy Express G2500, Van Cargo, 6.6 6SECTION Circuit/System Description
WARNING: This page is about a different car, the 2008 GMC Yukon and 2008 Chevrolet Tahoe. However, it is still accessible from the selected car via links, so may be relevant.

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.

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