Principles of Operation: Ms-Can

WARNING: This page is about a different car, the 2008 Ford RV Cutaway, 2008 Ford Econoline, 2008 Ford E450 Super Duty, and 2008 Ford Cutaway. However, it is still accessible from the selected car via links, so may be relevant.

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 network CAN circuits allowing multiple modules to communicate with each other and 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 designed for general information transfer.

The following modules are on the MS-CAN:

Instrument cluster (IC)
Vehicle security module (VSM)

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

MS-CAN 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 possible for all network modules
MS-CAN (+) open	Unreliable communication possible for all network modules
MS-CAN (-) open	Unreliable communication possible for all network modules
Module loss of voltage or ground	No communication
Module internal failure	No communication