Circuit/System Description

WARNING: This page is about a different car, the 2009 GMC Sierra, 2009 GMC Cab & Chassis Sierra, 2009 Chevrolet Silverado, and 2009 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

Modules connected to the high and low speed 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 SDGM energizes the wake up signal to activate the accessory DC power control module (APM) and another wake up signal to activate the hybrid powertrain control module (HPCM) which is inside the drive motor power inverter module (PIM). The HPCM reports all DTC for the APM, therefore DTC U189A cannot be reported with the HPCM is inoperative.