Module Communications Network: Overview Mercury Milan I

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, inter-module 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. Audio unit
2. Instrument cluster
3. SJB
4. Climate controlled seat module (if equipped)
5. THX® amplifier (if equipped)
6. DDM (if equipped)
7. DSM (if equipped)
8. EATC module (if equipped)
9. DATC module (if equipped)
10. Satellite radio receiver (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. RCM
3. TCM
4. ABS module
5. Instrument cluster
6. Occupant classification sensor module
7. 4WD control module

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), 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 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 FNR5 transaxle and the 6 speed transaxle both communicate on the HS-CAN network. 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 CBP18 (GY/OG), SBP07 (WH/RD) and SBB16 (VT/RD). Both circuits GD120 (BK/GN) provide ground.

Possible Causes

1. Fuse
2. Circuit CBP18 (GY/OG) open
3. Circuit GD120 (BK/GN) open
4. Circuit SBB16 (VT/RD) open
5. Circuit SBP07 (WH/RD) open
6. Circuit VDB04 (WH/BU) open (HS-CAN +)
7. Circuit VDB05 (WH) open (HS-CAN -)
8. 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), 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 circuit CBP19 (BN/WH). Ground is provided by circuit GD123 (BK/GY).

Possible Causes

1. Fuse
2. Circuit CBP19 (BN/WH) open
3. Circuit GD123 (BK/GY) open
4. Circuit VDB04 (WH/BU) open (HS-CAN +)
5. Circuit VDB05 (WH) open (HS-CAN -)
6. 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), 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 CBP21 (BU/GY), and the RCM is case grounded.

Possible Causes

1. Fuse
2. Circuit CBP21 (BU/GY) 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 the powertrain control module (PCM), the transmission control module (TCM), the anti-lock brake system (ABS) module, the restraints control module (RCM), the occupant classification sensor module and the instrument cluster. Voltage to the 4WD control module is supplied by circuits CBP19 (BN/WH) and SBP15 (WH/RD). Ground is supplied by circuit GD126 (BK/WH).

Possible Causes

1. Fuse
2. Circuit CBP19 (BN/WH) open
3. Circuit GD126 (BK/WH) open
4. Circuit SBP15 (WH/RD) open
5. Circuit VDB04 (WH/BU) open (HS-CAN +)
6. Circuit VDB05 (WH) open (HS-CAN -)
7. 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), the anti-lock brake system (ABS) module, the restraints control module (RCM), the 4WD control module (if equipped) and the instrument cluster. Voltage to the occupant classification sensor module is supplied by circuit CBP24 (VT/GN). Ground is supplied by circuit GD127 (BK/BU).

Possible Causes

1. Fuse
2. Circuit CBP24 (VT/GN) open
3. Circuit GD127 (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), the anti-lock brake system (ABS) module, the restraints 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 dual automatic temperature control (DATC) module (if equipped), the audio unit, the THX® amplifier (if equipped), the satellite radio receiver (if equipped), the driver seat module (DSM) (if equipped), the driver door module (DDM) (if equipped) and the climate controlled seat module (if equipped). Voltage for the instrument cluster is provided by circuits CBP23 (BN/YE), SBP07 (WH/RD) and CBP20 (YE/VT). Both circuits GD116 (BK/VT) provide ground.

Possible Causes

1. Fuse
2. Circuit CBP20 (YE/VT) open
3. Circuit CBP23 (BN/YE) open
4. Circuit GD116 (BK/VT) open
5. Circuit SBP07 (WH/RD) open
6. Circuit VDB04 (WH/BU) open (HS-CAN +)
7. Circuit VDB05 (WH) open (HS-CAN -)
8. 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 dual automatic temperature control (DATC) module (if equipped), the audio unit, the THX® amplifier (if equipped), the satellite radio receiver (if equipped), the driver seat module (DSM) (if equipped), the driver door module (DDM) (if equipped) and the climate controlled seat module (if equipped). Voltage for the SJB is provided by circuit SBB19 (BU/RD). Circuit GD116 (BK/VT) provides ground.

Possible Causes

1. Fuse
2. Circuit GD116 (BK/VT) open
3. Circuit SBB19 (BU/RD) 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 is only on vehicles equipped with automatic climate control. The EATC module shares the MS-CAN network with the smart junction box (SJB), the instrument cluster, the audio unit, the THX® amplifier (if equipped), the satellite radio receiver (if equipped), the driver seat module (DSM) (if equipped), the driver door module (DDM) (if equipped) and the climate controlled seat module (if equipped). Voltage for the EATC module is provided by circuits CBP20 (YE/VT) and SBP07 (WH/RD). Circuit GD116 (BK/VT) provides ground.

Possible Causes

1. Fuse
2. Circuit CBP20 (YE/VT) open
3. Circuit GD116 (BK/VT) open
4. Circuit SBP07 (WH/RD) open
5. Circuit VDB06 (GY/OG) open (MS-CAN +)
6. Circuit VDB07 (VT/OG) open (MS-CAN -)
7. EATC module

The DATC 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 DATC module. The DATC module is only on vehicles equipped with automatic climate control. The DATC module shares the MS-CAN network with the smart junction box (SJB), the instrument cluster, the audio unit, the THX® amplifier (if equipped), the satellite radio receiver (if equipped), the driver seat module (DSM) (if equipped), the driver door module (DDM) (if equipped) and the climate controlled seat module (if equipped). Voltage for the DATC module is provided by circuits CBP20 (YE/VT) and SBP07 (WH/RD). Circuit GD116 (BK/VT) provides ground.

Possible Causes

1. Fuse
2. Circuit CBP20 (YE/VT) open
3. Circuit GD116 (BK/VT) open
4. Circuit SBP07 (WH/RD) open
5. Circuit VDB06 (GY/OG) open (MS-CAN +)
6. Circuit VDB07 (VT/OG) open (MS-CAN -)
7. DATC module

There are 2 types of audio units used on this vehicle, the base audio unit (Audiophile) and the THX® audio unit (if equipped). Both audio units communicate with the scan tool through the medium speed controller area network (MS-CAN), circuits VDB06 (GY/OG) and VDB07 (VT/OG).

Circuits VDB06 (GY/OG) (MS-CAN +) and VDB07 (VT/OG) (MS-CAN -) provide the network connection to the audio unit. The audio unit shares the MS-CAN network with the instrument cluster, the electronic automatic temperature control (EATC) module (if equipped), the dual automatic temperature control (DATC) module (if equipped), the THX® amplifier (if equipped), the satellite radio receiver (if equipped), the driver seat module (DSM) (if equipped), the driver door module (DDM) (if equipped) and the climate controlled seat module (if equipped). Voltage for the audio unit is provided by circuits CBP02 (GN) and SBP11 (BU/RD). Circuit GD114 (BK/BU) provides ground.

Possible Causes

1. Fuse
2. Circuit CBP02 (GN) open
3. Circuit GD114 (BK/BU) open
4. Circuit SBP11 (BU/RD) open
5. Circuit VDB06 (GY/OG) open (MS-CAN +)
6. Circuit VDB07 (VT/OG) open (MS-CAN -)
7. Audio unit

The THX® amplifier 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 THX® amplifier. The THX® amplifier shares the MS-CAN network with the instrument cluster, the electronic automatic temperature control (EATC) module (if equipped), the dual automatic temperature control (DATC) module (if equipped), the audio unit, the satellite radio receiver (if equipped), the driver seat module (DSM) (if equipped), the driver door module (DDM) (if equipped) and the climate controlled seat module (if equipped). Voltage for the THX® amplifier is provided by circuits SBB20 (GN/RD) and SBB21 (GY/RD). Both circuits GD148 (BK/YE) provide ground.

Possible Causes

1. Fuse
2. Circuit GD148 (BK/YE) open
3. Circuit SBB20 (GN/RD) open
4. Circuit SBB21 (GY/RD) open
5. Circuit VDB06 (GY/OG) open (MS-CAN +)
6. Circuit VDB07 (VT/OG) open (MS-CAN -)
7. Audio unit

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 electronic automatic temperature control (EATC) module (if equipped), the dual automatic temperature control (DATC) module (if equipped), the audio unit, the THX® amplifier (if equipped), the driver seat module (DSM) (if equipped), the driver door module (DDM) (if equipped) and the climate controlled seat module (if equipped). Voltage for the satellite radio receiver is provided by circuit SBP15 (WH/RD). Circuit GD148 (BK/YE) provides ground.

Possible Causes

1. Fuse
2. Circuit GD148 (BK/YE) open
3. Circuit SBP15 (WH/RD) open
4. Circuit VDB06 (GY/OG) open (MS-CAN +)
5. Circuit VDB07 (VT/OG) open (MS-CAN -)
6. Satellite radio receiver

The DDM 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 DDM. The DDM shares the MS-CAN network with the smart junction box (SJB), the instrument cluster, the audio unit, the THX® amplifier (if equipped), the satellite radio receiver (if equipped), the driver seat module (DSM) (if equipped), and the climate controlled seat module (if equipped). Voltage for the DDM is provided by circuit SBP15 (RD/WH). Circuit GD126 (BK/WH) provides ground.

Possible Causes

1. Fuse
2. Circuit GD126 (BK/WH) open
3. Circuit SBP15 (RD/WH) open
4. Circuit VDB06 (GY/OG) open (MS-CAN +)
5. Circuit VDB07 (VT/OG) open (MS-CAN -)
6. DDM

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 smart junction box (SJB), the instrument cluster, the audio unit, the THX® amplifier (if equipped), the satellite radio receiver (if equipped), the driver door module (DDM) (if equipped), and the climate controlled seat module (if equipped). Voltage for the DSM is provided by circuit SBB15 (WH/RD). Circuit GD126 (BK/WH) provides ground.

Possible Causes

1. Fuse
2. Circuit GD126 (BK/WH) open
3. Circuit SBB15 (WH/RD) open
4. Circuit VDB06 (GY/OG) open (MS-CAN +)
5. Circuit VDB07 (VT/OG) open (MS-CAN -)
6. DSM

The climate controlled seat 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 climate controlled seat module. The climate controlled seat module shares the MS-CAN network with the smart junction box (SJB), the instrument cluster, the audio unit, the THX® amplifier (if equipped), the satellite radio receiver (if equipped), the driver door module (DDM) (if equipped), and the driver seat module (DSM) (if equipped). Voltage for the climate controlled seat module is provided by circuits SBB11 (BU/RD) and SBB12 (GN/RD). Circuit GD139 (BK/YE) provides ground.

Possible Causes

1. Fuse
2. Circuit GD139 (BK/YE) open
3. Circuit SBB11 (BU/RD) open
4. Circuit SBB12 (GN/RD) open
5. Circuit VDB06 (GY/OG) open (MS-CAN +)
6. Circuit VDB07 (VT/OG) open (MS-CAN -)
7. Climate controlled seat module

The MS-CAN uses an unshielded twisted pair cable, circuits VDB06 (GY/OG) and VDB07 (VT/OG). The smart junction box (SJB), the instrument cluster, the electronic automatic temperature control (EATC) module (if equipped), the dual automatic temperature control (DATC) module (if equipped), the audio unit, the THX® amplifier (if equipped), the satellite radio receiver (if equipped), the driver seat module (DSM) (if equipped), the driver door module (DDM) (if equipped) and the climate controlled seat module (if equipped) all communicate with the scan tool using the MS-CAN.

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. THX® amplifier (if equipped)
8. EATC module (if equipped)
9. DATC module (if equipped)
10. DDM (if equipped)
11. DSM (if equipped)
12. Climate controlled seat module (if equipped)
13. Satellite radio receiver (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. ABS module
6. TCM
7. 4WD control module (if equipped)
8. Instrument cluster
9. Occupant classification sensor module
10. RCM

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 SBP11 (BU/RD). Ground is provided by both circuits GD116 (BK/VT).

Possible Causes

1. Fuse
2. Circuit SBP11 (BU/RD) open
3. Circuit GD116 (BK/VT) open
4. Scan tool

Scheme 2

1. S1 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 S2 . NO : REPAIR the DLC as necessary. CLEAR the DTCs. REPEAT the network test with the scan tool.
2. S2 CHECK THE DLC VOLTAGE SUPPLY CIRCUIT SBP11 (BU/RD) FOR AN OPEN Measure the voltage between the DLC C251-16, circuit SBP11 (BU/RD), harness side and ground. Is the voltage greater than 10 volts? YES : Go to S3 . NO : VERIFY the smart junction box (SJB) fuse 18 (20A) is OK. If OK, REPAIR the circuit. REPEAT the network test with the scan tool.
3. S3 CHECK THE DLC GROUND CIRCUITS GD116 (BK/VT) FOR AN OPEN Measure the resistance between the DLC C251-4, circuit GD116 (BK/VT), harness side and ground; and between the DLC C251-5, circuit GD116 (BK/VT), 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.

See also:
• SEATING