Communications Network - Troubleshooting

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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 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 IC and the smart junction box (SJB) communications, and is designed for general information transfer. The MS-CAN 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 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 failures and their resulting symptom:MS-CAN Communication Fault Chart





HS-CAN

The HS-CAN 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 IC, the PCM, the ABS module, and 4X4 control module communications, and designed for real time information transfer and control. The HS-CAN 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 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 failures and their resulting symptom: HS-CAN Communication Fault Chart





Module Communication Message Charts

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