Section 5 (Electronic Control Modules (Service Information)): Communication: Description

WARNING: This page is about a different car, the 2017 Jeep Cherokee. However, it is still accessible from the selected car via links, so may be relevant.

The primary on-board communication network between microcontroller-based electronic control modules in this vehicle is the Controller Area Network (CAN) data 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. Multiplexing is any system that enables the transmission of multiple messages with modules over a single channel or circuit. In addition to the CAN bus network, certain nodes may also be equipped with a Local Interface Network (LIN) data bus. The LIN data bus is a single wire low-speed (9.6 Kbps) serial link bus used to provide direct communication between a LIN master module and certain switch or sensor inputs.

There are two separate CAN bus systems used in the vehicle. They are designated: the CAN-C, and the CAN-IHS. The CAN-C and CAN-IHS systems provide on-board communication between all of the nodes that are connected to them. The CAN-C system provides near real-time communication (500 Kbps) between more critical nodes; and the CAN-IHS system provides (125 Kbps) for less critical nodes.

The added speed of the CAN data bus is many times faster than previous data bus systems. This added speed facilitates the addition of more electronic control modules or nodes and the potential for more new electronic features in the vehicle.

The Body Control Module (BCM) or Central Gateway Module (CGW) is connected to the CAN-IHS and CAN-C buses. This gateway physically and electrically isolates the CAN buses from each other and coordinates the bi-directional transfer of messages between them. The BCM is located under the left hand side of the instrument panel.