Communication and Hosted Diagnostics
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.
In addition to the internal SPI bus communication circuit between the HPCM and each MCM, the MCMs also communicate on the Hi-speed and Hybrid GMLAN communication circuits. The MCM does not store its own diagnostic trouble code (DTC) information. The HPCM will store MCM associated DTC information for retrieval by a scan tool. The scan tool can communicate directly with each MCM in order to retrieve data parameters only.
The APM has internal diagnostic tests that run at both power-up and during operation. All DTCs from the APM are reported to and hosted by the HPCM. The APM communicates directly only with the HPCM and only on the high speed hybrid GMLAN communication circuit.