Module Communications Network: Overview Mercury Mountaineer III

Vehicle communication utilizes both medium and high speed controller area network (CAN) communications. CAN is used for many modules to communicate with each other on a common network. CAN in-vehicle networking, is a method for transferring data among distributed electronic modules via a serial data bus. Without serial networking, intermodule communication requires dedicated, point to point wiring resulting in bulky, expensive, complex, and difficult to install wiring harnesses. Applying a serial data network reduces the number of wires combining the signals on a single network. Information is sent to the individual control modules that control each function.

The vehicle has 2 module communication networks

1. Medium speed (MS) CAN
2. High speed (HS) CAN

Both networks are connected to the data link connector (DLC). This makes diagnosis and testing of these systems easier by allowing one scan tool to be able to diagnose and control any module on both networks from one connector. The DLC can be found under the instrument panel between the steering column and the audio unit.

Scheme 1

MS-CAN Network Operation

The MS-CAN network communicates using bussed messages. The MS-CAN has an unshielded twisted pair cable, data bus (+) and data bus (-) circuits. In addition to scan tool communication, this network allows sharing of information between all modules on the network.

The MS-CAN is a medium speed communication network used for the following modules

1. SJB
2. Audio unit
3. Instrument cluster
4. DSM (if equipped)
5. DVD player (if equipped)
6. EATC module (if equipped)
7. Parking aid module (if equipped)
8. Satellite audio receiver (if equipped)
9. Power running board module (if equipped)

HS-CAN Network Operation

The HS-CAN network communicates using bussed messages. The HS-CAN network uses an unshielded twisted pair cable, data bus (+) and data bus (-) circuits. In addition to scan tool communication, this network allows sharing of information between all modules on the network.

The HS-CAN is a high speed communication network used for the following modules

1. PCM
2. TCM (if equipped)
3. RCM
4. ABS module
5. Instrument cluster
6. Occupant classification sensor module
7. 4WD control module (if equipped)

Principles of Operation

Vehicle communication utilizes both 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. Medium speed (MS) CAN
2. High speed (HS) CAN

Normal Operation

The PCM communicates with the scan tool through the high speed controller area network (HS-CAN). Circuits VDB04 (WH/BU) (HS-CAN +) and VDB05 (WH) (HS-CAN -) provide the network connection to the PCM. The PCM shares the HS-CAN network with the transmission control module (TCM) (if equipped), the anti-lock brake system (ABS) module, the restraints control module (RCM), the four wheel drive (4WD) control module (if equipped), the occupant classification sensor module and the instrument cluster.

Possible Causes

1. Circuit VDB04 (WH/BU) open (HS-CAN +)
2. Circuit VDB05 (WH) open (HS-CAN -)
3. PCM

The 6R60 transmission utilizes a TCM to control transmission functions. The TCM communicates with the scan tool through the high speed controller area network (HS-CAN). Circuits VDB04 (WH/BU) (HS-CAN +) and VDB05 (WH) (HS-CAN -) provide the network connection to the TCM. The TCM shares the HS-CAN network with the powertrain control module (PCM), the anti-lock brake system (ABS) module, the restraints control module (RCM), the four wheel drive (4WD) control module (if equipped), the occupant classification sensor module and the instrument cluster. Voltage for the TCM is provided by circuits SBB27 (BU/RD) and CE517 (BU/GN). Circuit GD113 (BK/YE) provides ground.

Possible Causes

1. Fuse
2. Circuit CE517 (BU/GN) open
3. Circuit GD113 (BK/YE) open
4. Circuit SBB27 (BU/RD) open
5. Circuit VDB04 (WH/BU) open (HS-CAN +)
6. Circuit VDB05 (WH) open (HS-CAN -)
7. TCM

The ABS module communicates with the scan tool through the high speed controller area network (HS-CAN). Circuits VDB04 (WH/BU) (HS-CAN +) and VDB05 (WH) (HS-CAN -) provide the network connection to the ABS module. The ABS module shares the HS-CAN network with the powertrain control module (PCM), the transmission control module (TCM) (if equipped), the restraints control module (RCM), the four wheel drive (4WD) control module (if equipped), the occupant classification sensor module and the instrument cluster. Voltage for the ABS module is provided by circuits CBP18 (GY/OG), SBB06 (BN/RD) and SBB33 (RD). Ground is provided by circuit GD120 (BK/GN).

Possible Causes

1. Fuse
2. Circuit CBP18 (GY/OG) open
3. Circuit SBB06 (BN/RD) open
4. Circuit SBB33 (RD) open
5. Circuit GD120 (BK/GN) open
6. Circuit VDB04 (WH/BU) open (HS-CAN +)
7. Circuit VDB05 (WH) open (HS-CAN -)
8. ABS module

The RCM communicates with the scan tool through the high speed controller area network (HS-CAN). Circuits VDB04 (WH/BU) (HS-CAN +) and VDB05 (WH) (HS-CAN -) provide the network connection to the RCM. The RCM shares the HS-CAN network with the powertrain control module (PCM), the transmission control module (TCM) (if equipped), the anti-lock brake system (ABS) module, the four wheel drive (4WD) control module (if equipped), the occupant classification sensor module and the instrument cluster. Voltage for the RCM is provided by circuit CBP17 (BN/GN), and the RCM is case grounded.

Possible Causes

1. Fuse
2. Circuit CBP17 (BN/GN) open
3. Circuit VDB04 (WH/BU) open (HS-CAN +)
4. Circuit VDB05 (WH) open (HS-CAN -)
5. Case ground open
6. RCM

The 4WD control module communicates with the scan tool through the high speed controller area network (HS-CAN). Circuits VDB04 (WH/BU) (HS-CAN +) and VDB05 (WH) (HS-CAN -) provide the network connection to the 4WD control module. The 4WD control module shares the HS-CAN with powertrain control module (PCM), the transmission control module (TCM) (if equipped), the anti-lock brake system (ABS) module, the restraints control module (RCM), the occupant classification sensor module and the instrument cluster. Voltage is supplied by circuits CBP18 (GY/OG), SBB23 (RD/WH) and SBB26 (RD/BK). Ground is supplied by circuits GD138 (BK/WH) and GD145 (BK/BU).

Possible Causes

1. Fuse
2. Circuit CBP18 (GY/OG) open
3. Circuit GD138 (BK/WH) open
4. Circuit GD145 (BK/BU) open
5. Circuit SBB23 (RD/WH) open
6. Circuit SBB26 (RD/BK) open
7. Circuit VDB04 (WH/BU) open (HS-CAN +)
8. Circuit VDB05 (WH) open (HS-CAN -)
9. 4WD control module

The occupant classification sensor module communicates with the scan tool through the high speed controller area network (HS-CAN). Circuits VDB04 (WH/BU) (HS-CAN +) and VDB05 (WH) (HS-CAN -) provide the network connection to the occupant classification sensor module. The occupant classification sensor module shares the HS-CAN with the powertrain control module (PCM), the transmission control module (TCM) (if equipped), the anti-lock brake system (ABS) module, the restraints control module (RCM), the four wheel drive (4WD) control module (if equipped) and the instrument cluster. Voltage to the occupant classification sensor module is supplied by circuit CBP17 (BN/GN). Ground is supplied by circuit GD145 (BK/BU).

Possible Causes

1. Fuse
2. Circuit CBP17 (BN/GN) open
3. Circuit GD145 (BK/BU) open
4. Circuit VDB04 (WH/BU) open (HS-CAN +)
5. Circuit VDB05 (WH) open (HS-CAN -)
6. Occupant classification sensor module

The instrument cluster communicates with the scan tool through the high speed controller area network (HS-CAN). Circuits VDB04 (WH/BU) (HS-CAN +) and VDB05 (WH) (HS-CAN -) provide the HS-CAN network connection to the instrument cluster and circuits VDB06 (GY/OG) (MS-CAN +) and VDB07 (VT/OG) (MS-CAN -) provide the MS-CAN network connection to the instrument cluster. The instrument cluster shares the HS-CAN network with the powertrain control module (PCM), the transmission control module (TCM) (if equipped), the anti-lock brake system (ABS) module, the restraint control module (RCM), the four wheel drive (4WD) control module (if equipped) and the occupant classification sensor module. The instrument cluster shares the MS-CAN network with the smart junction box (SJB), the electronic automatic temperature control (EATC) module (if equipped), the audio unit, the satellite radio receiver (if equipped), the driver seat module (DSM) (if equipped), the parking aid module (if equipped), the power running board module (if equipped) and the digital versatile disc (DVD) player (if equipped). Voltage for the instrument cluster is provided by circuits CDC34 (WH/OG) and SBP24 (VT/RD). Circuit GD145 (BK/BU) provides ground.

Possible Causes

1. Fuse
2. Circuit CDC34 (WH/OG) open
3. Circuit GD145 (BK/BU) open
4. Circuit SBP24 (VT/RD) open
5. Circuit VDB04 (WH/BU) open (HS-CAN +)
6. Circuit VDB05 (WH) open (HS-CAN -)
7. Instrument cluster

The SJB communicates with the scan tool through the medium speed controller area network (MS-CAN). Circuits VDB06 (GY/OG) (MS-CAN +) and VDB07 (VT/OG) (MS-CAN -) provide the network connection to the SJB. The SJB shares the MS-CAN network with the instrument cluster, the electronic automatic temperature control (EATC) module (if equipped), the audio unit, the satellite radio receiver (if equipped), the driver seat module (DSM) (if equipped), the parking aid module (if equipped), the power running board module (if equipped), and the digital versatile disc (DVD) player (if equipped). Voltage for the SJB is provided by circuit SBB03 (BU/RD). Circuit GD108 (BK/VT) provides ground.

Possible Causes

1. Fuse
2. Circuit SBB03 (BU/RD) open
3. Circuit GD108 (BK/VT) open
4. Circuit VDB06 (GY/OG) open (MS-CAN +)
5. Circuit VDB07 (VT/OG) open (MS-CAN -)
6. SJB

The EATC module communicates with the scan tool through the medium speed controller area network (MS-CAN). Circuits VDB06 (GY/OG) (MS-CAN +) and VDB07 (VT/OG) (MS-CAN -) provide the network connection to the EATC module. The EATC module shares the MS-CAN network with the instrument cluster, the smart junction box (SJB), the audio unit, the satellite radio receiver (if equipped), the digital versatile disc (DVD) player (if equipped), the driver seat module (DSM) (if equipped), the power running board module (if equipped) and the parking aid module (if equipped). Voltage for the EATC module is provided by circuits CBP20 (YE/VT) and SBP28 (GN/RD). Circuit GD145 (BK/BU) provides ground.

Possible Causes

1. Fuse
2. Circuit CBP20 (YE/VT) open
3. Circuit GD145 (BK/BU) open
4. Circuit SBP28 (GN/RD) open
5. Circuit VDB06 (GY/OG) open (MS-CAN +)
6. Circuit VDB07 (VT/OG) open (MS-CAN -)
7. EATC module

The satellite radio receiver communicates with the scan tool through the medium speed controller area network (MS-CAN). Circuits VDB06 (GY/OG) (MS-CAN +) and VDB07 (VT/OG) (MS-CAN -) provide the network connection to the satellite radio receiver. The satellite radio receiver shares the MS-CAN network with the instrument cluster, the smart junction box (SJB), the electronic automatic temperature control (EATC) module (if equipped), the audio unit, the digital versatile disc (DVD) player (if equipped), the driver seat module (DSM) (if equipped), the power running board module (if equipped), and the parking aid module (if equipped). Voltage for the satellite radio receiver is provided by circuit SBB41 (RD). Circuit GD114 (BK/BU) provides ground.

Possible Causes

1. Fuse
2. Circuit GD114 (BK/BU) open
3. Circuit SBB41 (RD) open
4. Circuit VDB06 (GY/OG) open (MS-CAN +)
5. Circuit VDB07 (VT/OG) open (MS-CAN -)
6. Satellite radio receiver

The DVD player communicates with the scan tool through the medium speed controller area network (MS-CAN). Circuits VDB06 (GY/OG) (MS-CAN +) and VDB07 (VT/OG) (MS-CAN -) provide the network connection to the DVD player. The DVD player is only on vehicles equipped with rear seat entertainment. The DVD player shares the MS-CAN network with the instrument cluster, the smart junction box (SJB), the electronic automatic temperature control (EATC) module (if equipped), the audio unit, the satellite radio receiver (if equipped), the driver seat module (DSM) (if equipped), the digital versatile disc (DVD) player (if equipped), the power running board module (if equipped), and the parking aid module (if equipped). Voltage for the DVD player is provided by circuit SBB41 (RD). Circuit GD114 (BK/BU) provides ground.

Possible Causes

1. Fuse
2. Circuit GD114 (BK/BU) open
3. Circuit SBB41 (RD) open
4. Circuit VDB06 (GY/OG) open (MS-CAN +)
5. Circuit VDB07 (VT/OG) open (MS-CAN -)
6. DVD player

The DSM communicates with the scan tool through the medium speed controller area network (MS-CAN). Circuits VDB06 (GY/OG) (MS-CAN +) and VDB07 (VT/OG) (MS-CAN -) provide the network connection to the DSM. The DSM shares the MS-CAN network with the instrument cluster, the smart junction box (SJB), the electronic automatic temperature control (EATC) module (if equipped), the audio unit, the digital versatile disc (DVD) player (if equipped), the satellite radio receiver (if equipped), the power running board module (if equipped) and the parking aid module (if equipped). Voltage for the DSM is provided by circuit SBP01 (RD). Circuit GD143 (BK/OG) provides ground.

Possible Causes

1. Fuse
2. Circuit GD143 (BK/OG) open
3. Circuit SBP01 (RD) open
4. Circuit VDB06 (GY/OG) open (MS-CAN +)
5. Circuit VDB07 (VT/OG) open (MS-CAN -)
6. DSM

The power running board module communicates with the scan tool through the medium speed controller area network (MS-CAN). Circuits VDB06 (GY/OG) (MS-CAN +) and VDB07 (VT/OG) (MS-CAN -) provide the network connection to the power running board module. The power running board module shares the MS-CAN network with the instrument cluster, the smart junction box (SJB), the electronic automatic temperature control (EATC) module (if equipped), the audio unit, the digital versatile disc (DVD) player (if equipped), the driver seat module (DSM) (if equipped), the satellite radio receiver (if equipped), and the parking aid module (if equipped). Voltage for the power running board module is provided by circuit SBB19 (BU/RD). Circuit GD151 (BK/GN) provides ground.

Possible Causes

1. Fuse
2. Circuit GD151 (BK/GN) open
3. Circuit SBB19 (BU/RD) open
4. Circuit VDB06 (GY/OG) open (MS-CAN +)
5. Circuit VDB07 (VT/OG) open (MS-CAN -)
6. Power running board module

The parking aid module communicates with the scan tool through the medium speed controller area network (MS-CAN). Circuits VDB06 (GY/OG) (MS-CAN +) and VDB07 (VT/OG) (MS-CAN -) provide the network connection to the parking aid module. The parking aid module shares the MS-CAN network with the instrument cluster, the smart junction box (SJB), the electronic automatic temperature control (EATC) module (if equipped), the audio unit, the digital versatile disc (DVD) player (if equipped), the satellite radio receiver (if equipped), and the power running board module (if equipped). Voltage for the parking aid module is provided by circuit CBP18 (GY/OG). Circuit GD145 (BK/BU) provides ground.

Possible Causes

1. Fuse
2. Circuit CBP18 (GY/OG) open
3. Circuit GD145 (BK/BU) open
4. Circuit VDB06 (GY/OG) open (MS-CAN +)
5. Circuit VDB07 (VT/OG) open (MS-CAN -)
6. Parking aid module

The MS-CAN network uses an unshielded twisted pair cable, circuits VDB06 (GY/OG) and VDB07 (VT/OG) provide the network connection to all modules on the network. The smart junction box (SJB), the instrument cluster, the electronic automatic temperature control (EATC) module (if equipped), the audio unit, the satellite radio receiver (if equipped), the digital versatile disc (DVD) (if equipped), the power running board module (if equipped), the parking aid module (if equipped), and the driver seat module all communicate with the scan tool using the MS-CAN network.

Possible Causes

1. Circuit VDB06 (GY/OG) open, short to ground or voltage (MS-CAN +)
2. Circuit VDB07 (VT/OG) open, short to ground or voltage (MS-CAN -)
3. Circuit VDB06 (GY/OG) (MS-CAN +) and circuit VDB07 (VT/OG) (MS-CAN -) shorted together
4. SJB
5. Instrument cluster
6. Audio unit
7. EATC module (if equipped)
8. DVD player (if equipped)
9. Driver seat module (DSM) (if equipped)
10. Satellite radio receiver (if equipped)
11. Power running board module (if equipped)
12. Parking aid module (if equipped)

The HS-CAN uses an unshielded twisted pair cable, circuits VDB04 (WH/BU) and VDB05 (WH). The powertrain control module (PCM), the transmission control module (TCM), the anti-lock brake system (ABS) module, the restraints control module (RCM), the four wheel drive (4WD) control module (if equipped), the occupant classification sensor module and the instrument cluster all communicate with the scan tool using the HS-CAN.

Possible Causes

1. Circuit VDB04 (WH/BU) open, short to ground or voltage (HS-CAN +)
2. Circuit VDB05 (WH) open, short to ground or voltage (HS-CAN -)
3. Circuit VDB04 (WH/BU) (HS-CAN +) and circuit VDB05 (WH) (HS-CAN -) shorted together
4. PCM
5. RCM
6. ABS module
7. Instrument cluster
8. TCM (if equipped)
9. 4WD control module (if equipped)
10. Occupant classification sensor module

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) communications network. Voltage for the scan tool is provided by circuit SBP04 (GN/RD). Ground is provided by circuits GD108 (BK/VT) and GD138 (BK/WH).

Possible Causes

1. Fuse
2. Circuit SBP04 (GN/RD) open
3. Circuit GD108 (BK/VT) open
4. Circuit GD138 (BK/WH) open
5. Scan tool

Scheme 2

1. R1 CHECK THE DLC PINS FOR DAMAGE NOTE: Most faults are due to connector and/or wiring concerns. Carry out a thorough inspection and verification before proceeding with the pinpoint test. Disconnect the scan tool cable from the DLC. Inspect DLC pins 4, 5 and 16 for damage. Are DLC pins 4, 5 and 16 OK? YES : Go to R2 . NO : REPAIR the DLC as necessary. CLEAR the DTCs. REPEAT the network test with the scan tool.
2. R2 CHECK THE DLC VOLTAGE SUPPLY CIRCUIT SBP04 (GN/RD) FOR AN OPEN Measure the voltage between the DLC C251-16, circuit SBP04 (GN/RD), harness side and ground. Is the voltage greater than 10 volts? YES : Go to R3 . NO : VERIFY the smart junction box (SJB) fuse 4 (20A) is OK. If OK, REPAIR the circuit. REPEAT the network test with the scan tool.
3. R3 CHECK THE DLC GROUND CIRCUITS FOR AN OPEN Measure the resistance between the DLC C251-5, circuit GD108 (BK/VT), harness side and ground; and between the DLC C251-4, circuit GD138 (BK/WH), harness side and ground. Are the resistances less than 5 ohms? YES : REPAIR the scan tool. REPEAT the network test with the scan tool. NO : REPAIR the circuit in question. REPEAT the network test with the scan tool.