Hybrid Bus
The primary on-board communication network between microprocessor-based electronic control modules in this vehicle is the DaimlerChrysler Programmable Communication Interface (PCI) data bus system in combination with the Controller Area Network (CAN) data bus system, which forms a hybrid bus system. A data bus network minimizes redundant wiring connections; and, at the same time, reduces wire harness complexity, sensor current loads and controller hardware by allowing each sensing device to be connected to only one module (also referred to as a node). Each node reads, then broadcasts its sensor data over the bus for use by all other nodes requiring that data. Each node ignores the messages on the bus that it cannot use.
The CAN bus is a two-wire multiplex system, while the PCI bus is a single-wire multiplex system. Multiplexing is any system that enables the transmission of multiple messages over a single channel or circuit. Depending upon the optional equipment in the vehicle, the PCI bus is used for communication between most all body interior nodes, while the CAN-C bus is used exclusively by certain powertrain and chassis nodes in vehicles equipped with the hybrid bus.
In addition to the CAN and PCI bus networks, certain nodes may also be equipped with a Serial Controller Interface (SCI) or a K-Line serial link bus to provide direct diagnostic access between a diagnostic scan tool connected to the industry-standard 16-way Data Link Connector (DLC) located below the driver side instrument panel and certain powertrain nodes. The Bus Connections table identifies those nodes in this vehicle with more than one possible bus connection configuration. Those nodes that are not listed in the table are all connected to and accessed through the PCI bus.
| BUS CONNECTIONS | ||||||||
|---|---|---|---|---|---|---|---|---|
| NODE | BCM | CAB | ECM | PCM | SAS | TCM | YAW | |
| ALSO KNOWN AS | BCMCGW, Body Controller | ABM, ABS, ESP Controller | Diesel Engine Controller | NGC, Gas Engine Controller | Steering Angle Sensor | EATX, Transmission Controller | Yaw, Lateral G Sensor | |
| OPTIONS | w/Central Gateway | w/ABS & ESP Only | w/Diesel Only | w/Gas Only | - | w/ATX Only | - | |
| Gas Engine | *COMM | PCI & CAN | CAN | - | CAN | CAN | PCI | **CAN |
| *DIAG | PCI | CAN | - | CAN | CAN | PCI/SCI | **CAN | |
| *FLASH | PCI | CAN | - | CAN | CAN | SCI | **CAN | |
| Diesel Engine w/MTX | *COMM | PCI & CAN | CAN | CAN | - | CAN | - | **CAN |
| *DIAG | PCI | CAN | ***K-LINE | - | CAN | - | **CAN | |
| *FLASH | PCI | CAN | ***K-LINE | - | CAN | - | **CAN | |
| Diesel Engine w/ATX | *COMM | PCI & CAN | CAN | CAN | - | CAN | - | **CAN |
| *DIAG | PCI | CAN | ***K-LINE | - | CAN | - | **CAN | |
| *FLASH | PCI | CAN | ***K-LINE | - | CAN | - | **CAN | |
| Notes | ||||||||
| *FUNCTIONS | COMM = Intravehicle Communication | |||||||
| DIAG = Scan Tool Diagnostic Communication | ||||||||
| FLASH = Flash Reprogramming Access | ||||||||
| **CAN | This is a dedicated CAN-C bus line between the Yaw Sensor and the CAB. | |||||||
| ***K-LINE | The K-Line bus may also referred to as the Serial Controller Interface (SCI) bus in some diagnostic information. | |||||||
The added speed of the CAN and PCI hybrid data bus network is many times faster than previous data bus systems. This added speed facilitates the addition of more electronic control modules or nodes and the incorporation of many new electrical and electronic features in the vehicle.
The hybrid bus system has a Central Gate Way (CGW) or hub integral to a Body Control Module (BCM or BCMCGW) that is connected to both buses. This gateway physically and electrically isolates the CAN and PCI buses from each other and coordinates the bi-directional transfer of messages between them. The BCM is located on the Junction Block (JB), which is located on the driver side instrument panel end bracket in the passenger compartment of the vehicle.