Circuit Description
The vehicle is fitted with a new powertrain interface module (PIM). The most significant changes that have been made to the PIM are as follows:
| • | Communication protocol between the engine control module (ECM), transmission control module (TCM) and the Electronic Control Unit (ECU) of the Antilock Braking and Traction Control System, is General Motors Local Area Network (GM LAN) . |
| • | ECM to PIM and PIM to body control module (BCM) authentication for vehicle security. |
| • | Cruise control switch functions input directly into the PIM. |
| • | Traction control enable/disable switch inputs directly into the PIM. |
The various electronic control modules integrated into the vehicle communicate with each other through the serial data bus. The ECM, TCM and ECU of the ABS-TCS communicate on the serial data bus using the GM LAN communication protocol, while the BCM communicates with the instrument cluster, Audio Head Unit (AHU) and Occupant Protection System Sensing and Diagnostic Module (SDM) using the universal asynchronous receive and transmit (UART) communication protocol.
The PIM is integrated into the serial data network and acts as a transparent bi-directional translation device that enables the control modules on the GM LAN serial data bus to communicate with control modules on the UART serial data bus.
