Principles of Operation: Ms-Can

WARNING: This page is about a different car, the 2007 Mercury Mariner and 2007 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.

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

MS-CAN NETWORK COMMUNICATION FAULT CHART

Failure Description	Symptom
MS-CAN (+) shorted to MS-CAN (-)	No communication
MS-CAN (+) short to voltage	No communication
MS-CAN (-) short to voltage	No communication
MS-CAN (+) short to ground	No communication
MS-CAN (-) short to ground	Unreliable communication
MS-CAN (+) open	Unreliable communication
MS-CAN (-) open	Unreliable communication
Module loss of voltage or ground	No communication
Module internal failure	No communication