Communications Network - Troubleshooting

COMMUNICATIONS NETWORK - TROUBLESHOOTING
See the Tribute Wiring Diagram for schematic information.

Principles of Operation
Vehicle communication utilizes the controller area network (CAN) communications. The CAN is a method for transferring data among distributed electronic modules via a serial data bus.

The vehicle is equipped with 2 module communication networks:
- Medium speed (MS) CAN
- High speed (HS) CAN

MS-CAN
The MS-CAN network uses an unshielded twisted pair cable of data (+) and data (-) circuits. The data (+) and the data (-) circuits are each regulated to approximately 2.5 volts during neutral or rested network traffic. As bus messages are sent on the data (+) circuit, voltage is increased by approximately 1.0 volt. Inversely, the data (-) circuit is reduced by approximately 1.0 volt when a bus message is sent. Multiple bus messages can be sent over the CAN circuits allowing multiple modules to communicate with each other. The MS-CAN is used for the instrument cluster and the smart junction box (SJB) communications, and is designed for general information transfer. The MS-CAN network will not communicate while certain faults are present, but will operate with diminished performance with other faults present. The MS-CAN bus may remain operational when 1 of the 2 termination resistors are not present.

The MS-CAN network operates at a maximum data transfer speed of 125 Kbps for bus messages and is designed for general information transfer. The network will remain operational, but at a degraded level when certain circuit faults are present.

The following fault chart describes the specific MS-CAN network failures and their resulting symptom:






HS-CAN
The HS-CAN network uses an unshielded twisted pair cable of data (+) and data (-) circuits. The data (+) and the data (-) circuits are each regulated to approximately 2.5 volts during neutral or rested network traffic. As bus messages are sent on the data (+) circuit, voltage is increased by approximately 1.0 volt. Inversely, the data (-) circuit is reduced by approximately 1.0 volt when a bus message is sent. Multiple bus messages can be sent over the CAN circuits allowing multiple modules to communicate with each other. The HS-CAN is a high speed communication network used for the instrument cluster, the PCM, the ABS module, and the four wheel drive (4WD) control module communications, and designed for real time information transfer and control. The HS-CAN network will not communicate while certain faults are present, but will operate with diminished performance with other faults present. The HS-CAN bus may remain operational when 1 of the 2 termination resistors are not present.

The HS-CAN network operates at a maximum data transfer speed of 500 Kbps and is designed for real time information transfer and control. The network will remain operational, but at a degraded level when certain circuit faults are present.

The following fault chart describes the specific HS-CAN network failures and their resulting symptom:

HS-CAN Network Communication Fault Chart:

Module Communication Message Charts
The following charts describes the specific CAN network messages broadcast by each module, and the module(s) that receive the message: