Circuit/System Description

Modules connected to the high speed hybrid GMLAN serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module.

The communication enable and the wakeup circuits are energized by a specific module to activate another specific module when the ignition key is in ACC, ON or START. Only the modules using high speed GMLAN serial data are connected to the enable or wakeup circuits. Refer to the schematics to determine which modules activate and are activated using the enable or wakeup circuits.

The motor control module (MCM) 1, 2, and the hybrid powertrain control module (HPCM) are all internal to the drive motor power inverter module (PIM). The MCMs communicate only with the HPCM with the HPCM sending out DTC information to other modules regarding the MCMs. All circuits to the MCM are also internal to the PIM and is replaced as a single component.

Communication diagnostics for the serial data, including module power and ground as well as the wakeup circuits for both MCMs, and the HPCM are all diagnosed from external sources only to the PIM connector because any circuit fault condition within the PIM will cause a complete replacement.