Principles of Operation: Ms-Can

The MS-CAN is a medium speed communication network that 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 network CAN circuits allowing multiple modules to communicate with each other. 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 network 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 designed for general information transfer. The network will remain operational, but at a degraded level when certain circuit faults are present. The MS-CAN network may remain operational with only one termination resistor present.

The following modules are on the MS-CAN network:

• Smart junction box (SJB)
• Instrument cluster
• Audio unit
• THX® amplifier (if equipped)
• Satellite radio receiver (if equipped)
• Electronic automatic temperature control (EATC) module (if equipped)
• Dual automatic temperature control (DATC) module (if equipped)
• Driver seat module (DSM) (if equipped)
• Driver door module (DDM) (if equipped)
• Climate controlled seat module (if equipped)

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