Circuit/System Description

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 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 enable signal circuit is energized by the body control module (BCM) to activate multiple modules when the BCM determines that communication is required. Some modules may still become active due to their own ignition voltage source if the enable circuit is not functional. The serial data gateway (SDG) module translates serial data messages between the high speed GMLAN serial data bus, the low speed GMLAN serial data bus, and the high speed hybrid GMLAN serial data bus. Messages between the drive motor generator battery control module and the other hybrid system control modules must pass thru the SDG module. DTC U1862 is set by the drive motor generator battery control module, but is stored in and reported by the hybrid powertrain control module (HPCM).