Communication and Hosted Diagnostics: Notes

The HPCM is the host controller for diagnostic trouble code (DTC) information for the following control modules:

• Accessory DC power control module (APM)
• Battery energy control module (BECM)
• Motor control module (MCM) 1
• Motor control module (MCM) 2
• Auxiliary transmission fluid pump (ATFP) control module

These modules diagnose their own operation and determine when a fault condition is present. Diagnostic status is communicated to the HPCM through the following circuits:

• APM utilizes the GM Hi-speed, Hybrid LAN communication circuit
• BECM utilizes the GM Hi-speed, Hybrid LAN communication circuit
• Each MCM and the HPCM exchange information and commands on the SPI bus internal communication circuit as well as the hi-speed hybrid GMLAN communication circuit.
• ATFP control module utilizes a dedicated diagnostic status circuit

In the event a hosted module communicates a fault condition, the HPCM will determine if hybrid operation is effected and notify the vehicle operator by requesting the MIL illuminate and/or by displaying a hybrid service required message. In addition, the HPCM will store the associated DTC information for retrieval by a scan tool. Some hosted modules may require an ignition cycle to clear certain DTCs from the HPCM.