Module Communications Network: Overview Ford Transit VII

Multiplexing is a method of sending 2 or more signals simultaneously over a single circuit. Multiplexing is used to allow 2 or more electronic modules (nodes) to communicate simultaneously over a twisted-wire pair [data (+) and data (-)] network. The information or messages that can be communicated on these wires consists of commands, status or data. The advantage of using multiplexing is to reduce the weight of the vehicle by reducing the number of redundant components and electrical wiring.

The vehicle has 3 module communication networks which are connected to the Data Link Connector (DLC), located under the driver side of the instrument panel

1. High Speed Controller Area Network (HS-CAN)
2. Medium Speed Controller Area Network (MS-CAN)
3. ISO

Scheme 1

TERMINATION MODULE REFERENCE CHART

Principles of Operation

Vehicle communication utilizes both ISO and Controller Area Network (CAN) communications.

Both the High Speed Controller Area Network (HS-CAN) and the Medium Speed Controller Area Network (MS-CAN) use an unshielded twisted-pair cable of data (+) and data (-) circuits. The HS-CAN operates at a maximum data transfer speed of 500 Kbps and is designed for applications in which modules must respond as rapidly as required by the driver or needed by the process being controlled. The MS-CAN operates at a maximum data transfer speed of 125 Kbps for bus messages and is designed for general information transfer.

The ISO communications network is a single wire network. The ISO communications network does not permit intermodule communication and is for diagnostic use only.

Normal Operation

The PCM communicates with the scan tool through the High Speed Controller Area Network (HS-CAN).

This pinpoint test is intended to diagnose the following

1. Wiring, terminals or connectors
2. PCM

The ABS module communicates with the scan tool through the High Speed Controller Area Network (HS-CAN).

This pinpoint test is intended to diagnose the following

1. Fuse
2. Wiring, terminals or connectors
3. ABS module

The Instrument Cluster (IC) communicates with the scan tool and other network modules on the High Speed Controller Area Network (HS-CAN). The IC communicates with other network modules on the Medium Speed Controller Area Network (MS-CAN).

This pinpoint test is intended to diagnose the following

1. Fuse(s)
2. Wiring, terminals or connectors
3. IC

The PAM communicates with the scan tool through the ISO communications network.

This pinpoint test is intended to diagnose the following

1. Fuse
2. Wiring, terminals or connectors
3. PAM

The Audio Control Module (ACM) communicates with the scan tool through the Medium Speed Controller Area Network (MS-CAN).

This pinpoint test is intended to diagnose the following

1. Fuse
2. Wiring, terminals or connectors
3. ACM

The Speech Recognition Module (SRM) communicates with the scan tool through the Medium Speed Controller Area Network (MS-CAN).

This pinpoint test is intended to diagnose the following

1. Fuse
2. Wiring, terminals or connectors
3. SRM

The Occupant Classification System Module (OCSM) communicates with the scan tool through the Medium Speed Controller Area Network (MS-CAN).

This pinpoint test is intended to diagnose the following

1. Fuse
2. Wiring, terminals or connectors
3. OCSM

The Restraints Control Module (RCM) communicates with the scan tool through the Medium Speed Controller Area Network (MS-CAN).

This pinpoint test is intended to diagnose the following

1. Fuse
2. Wiring, terminals or connectors
3. Case ground open
4. RCM

The Tire Pressure Monitoring System (TPMS) module communicates with the scan tool through the Medium Speed Controller Area Network (MS-CAN).

This pinpoint test is intended to diagnose the following

1. Fuse
2. Wiring, terminals or connectors
3. TPMS module

The Generic Electronic Module (GEM) communicates with the scan tool through the Medium Speed Controller Area Network (MS-CAN).

This pinpoint test is intended to diagnose the following

1. Fuse
2. Wiring, terminals or connectors
3. GEM

The Medium Speed Controller Area Network (MS-CAN) uses an unshielded twisted pair cable, circuits 4-EC1 (GY/RD)/4-EC13 (GY/VT)/4-EC14 (GY/OG) and 5-EC1 (BU/RD)/5-EC13 (BU/WH)/5-EC14 (BU/BK). The Instrument Cluster (IC), while on the MS-CAN , communicates with the scan tool only on the High Speed Controller Area Network (HS-CAN).

This pinpoint test is intended to diagnose the following

1. Data Link Connector (DLC)
2. Wiring, terminals or connectors
3. Audio Control Module (ACM)
4. Generic Electronic Module (GEM)
5. IC
6. Occupant Classification System Module (OCSM)
7. Restraints Control Module (RCM)
8. Speech Recognition Module (SRM) (if equipped)
9. Tire Pressure Monitoring System (TPMS) module

The Medium Speed Controller Area Network (MS-CAN) uses an unshielded twisted pair cable.

In the event that either the MS-CAN (+) or MS-CAN (-) circuit becomes open to a module on the network, unreliable network communication to all modules on the network may result.

This pinpoint test is intended to diagnose the following

1. Wiring, terminals or connectors
2. Data Link Connector (DLC)

The High Speed Controller Area Network (HS-CAN) uses an unshielded twisted pair cable

This pinpoint test is intended to diagnose the following

1. Fuse
2. Wiring, terminals or connectors
3. Data Link Connector (DLC)
4. ABS module
5. Instrument Cluster (IC)
6. Steering Angle Sensor Module (SASM) (if equipped)
7. PCM

The High Speed Controller Area Network (HS-CAN) uses an unshielded twisted pair cable.

In the event that either the HS-CAN (+) or HS-CAN (-) circuit becomes open to a module on the network, unreliable network communication to all modules on the network may result.

This pinpoint test is intended to diagnose the following

1. Wiring, terminals or connectors
2. Data Link Connector (DLC)

The scan tool is connected to the Data Link Connector (DLC) to communicate with the High Speed Controller Area Network (HS-CAN) and Medium Speed Controller Area Network (MS-CAN).

A loss of ground or poor ground at the DLC may result in HS-CAN or MS-CAN faults while the scan tool is connected.

This pinpoint test is intended to diagnose the following

1. Fuse
2. Wiring, terminals or connectors
3. DLC
4. Scan tool

See also:
• SUPPLEMENTAL RESTRAINT SYSTEM