Module Communications Network: Overview Ford Flex I

Note. The Smart Junction Box (SJB) is also known as the Generic Electronic Module (GEM).

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 2 module communication networks which are connected to the Data Link Connector (DLC), located under the instrument panel

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

Scheme 1

NETWORK REFERENCE CHART

Principles of Operation

Note. The Smart Junction Box (SJB) is also known as the Generic Electronic Module (GEM).

Vehicle communication utilizes both the medium and high speed Controller Area Network (CAN) communications. 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

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

Normal Operation

The PCM communicates with the scan tool through the High Speed Controller Area Network (HS-CAN). An Integrated Diagnostic System (IDS) session cannot be established if PCM communication fails when attempting to identify the vehicle.

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 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. IC

The Restraints Control Module (RCM) 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. Case ground
4. RCM

The Occupant Classification System Module (OCSM) 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. OCSM

The 4X4 control 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. 4X4 control module

The Power Steering Control Module (PSCM) 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. PSCM (part of the steering gear - Electronic Power Assist Steering (EPAS))

The Steering Angle Sensor Module (SASM) 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. SASM

The Parking Aid Module (PAM) 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. PAM

The HVAC 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. HVAC module

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 audio Digital Signal Processing (DSP) 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. Audio DSP module

The Front Controls Interface Module (FCIM) 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. FCIM

The Front Display Interface Module (FDIM) 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. FDIM

The Driver Seat Module (DSM) 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. DSM

The Rear Entertainment Module (RETM) 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. RETM

The Liftgate/Trunk Module (LTM) 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. LTM

The Smart Junction Box (SJB) 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. SJB

The Global Positioning System Module (GPSM) 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. GPSM

The Accessory Protocol Interface Module (APIM) 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. APIM

The High Speed Controller Area Network (HS-CAN) uses an unshielded twisted pair cable. In the event that 1 of the 2 network circuits ( HS-CAN + or HS-CAN -) becomes open to a module on the network, unreliable network communication to all modules on the network can result.

The following modules communicate with the scan tool using the HS-CAN

1. 4X4 control module
2. ABS module
3. Accessory Protocol Interface Module (APIM)
4. Instrument Cluster (IC)
5. Occupant Classification System Module (OCSM)
6. Parking Aid Module (PAM)
7. PCM
8. Power Steering Control Module (PSCM)
9. Restraints Control Module (RCM)
10. Steering Angle Sensor Module (SASM)

This pinpoint test is intended to diagnose the following

1. Wiring, terminals or connectors

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

This pinpoint test is intended to diagnose the following

1. Wiring, terminals or connectors
2. 4X4 control module
3. ABS module
4. Accessory Protocol Interface Module (APIM)
5. Instrument Cluster (IC)
6. Occupant Classification System Module (OCSM)
7. Parking Aid Module (PAM)
8. PCM
9. Power Steering Control Module (PSCM)
10. Restraints Control Module (RCM)
11. Steering Angle Sensor Module (SASM)

The Medium Speed Controller Area Network (MS-CAN) uses an unshielded twisted pair cable. In the event that 1 of the 2 network circuits ( MS-CAN + or MS-CAN -) becomes open to a module on the network, unreliable network communication to all modules on the network can result.

The following modules communicate with the scan tool using the MS-CAN

1. Audio Control Module (ACM)
2. Accessory Protocol Interface Module (APIM)
3. Audio Digital Signal Processing (DSP) module
4. Driver Seat Module (DSM)
5. Front Controls Interface Module (FCIM)
6. Front Display Interface Module (FDIM)
7. Global Positioning System Module (GPSM)
8. HVAC module
9. Instrument Cluster (IC)
10. Liftgate/Trunk Module (LTM)
11. Rear Entertainment Module (RETM)
12. Smart Junction Box (SJB)

This pinpoint test is intended to diagnose the following

1. Wiring, terminals or connectors

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

This pinpoint test is intended to diagnose the following

1. Wiring, terminals or connectors
2. Audio Control Module (ACM)
3. Accessory Protocol Interface Module (APIM)
4. Audio Digital Signal Processing (DSP) module
5. Driver Seat Module (DSM)
6. Front Controls Interface Module (FCIM)
7. Front Display Interface Module (FDIM)
8. Global Positioning System Module (GPSM)
9. HVAC module
10. Instrument Cluster (IC)
11. Liftgate/Trunk Module (LTM)
12. Rear Entertainment Module (RETM)
13. Smart Junction Box (SJB)

The scan tool is connected to the Data Link Connector (DLC) to communicate with the High Speed Controller Area Network (HS-CAN) and the Medium Speed Controller Area Network (MS-CAN). A loss of ground or poor ground at the DLC can 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. Scan tool

See also:
• SUPPLEMENTAL RESTRAINT SYSTEM