Communication and Hosted Diagnostics: Notes
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 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.