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Module Communications Network System: Overview Ford Ranger II

Communication Devices 2 illustrations ~1321 words

Vehicle communication utilizes both International Standards Organization (ISO) 9141 and controller area network (CAN) communications. ISO 9141 is used for diagnostic use only, and 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 individual control modules that control each function.

The vehicle has 2 module communication networks

  1. ISO 9141
  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.

Scheme 1

Scheme 1
Scheme 1
Module NameNetwork TypeTermination Module
Anti-lock brake system (ABS) moduleISON/A
Instrument cluster (IC)HS-CANYes
Four wheel drive (4WD) control moduleHS-CANNo
Occupant classification sensor (OCS) moduleHS-CANNo
Powertrain control module (PCM)HS-CANYes
Restraints control module (RCM)HS-CANNo
Smart junction box (SJB)HS-CANNo

ISO 9141 Network Operation

The ISO 9141 communications network is a single wire network. The ISO 9141 communication network is used only by the ABS module.

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. SJB
  4. 4WD control module
  5. Occupant classification sensor module
  6. Instrument cluster

Principles of Operation

Vehicle communication utilizes both International Standards Organization (ISO) 9141 and controller area network (CAN) communications. ISO 9141 is used for diagnostic use only, and CAN is a method for transferring data among distributed electronic modules via a serial data bus.

The vehicle is equipped with 2 communication networks

  1. ISO 9141
  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 with the four wheel drive (4WD) control module, the restraints control module (RCM), the occupant classification sensor module, the smart junction box (SJB), and the instrument cluster. Circuits CBB39 (VT/WH) and SBB21 (GY/RD) provide voltage, and redundant circuit GD108 (BK/VT) provides ground.

Possible Causes

  1. Fuse
  2. Circuit CBB39 (VT/WH) open
  3. Circuit SBB21 (GY/RD) open
  4. Circuit GD108 (BK/VT) open
  5. Circuit VDB04 (WH/BU) open, short to ground or voltage (HS-CAN +)
  6. Circuit VDB05 (WH) open, short to ground or voltage (HS-CAN -)
  7. Circuit VDB04 (WH/BU) (HS-CAN +) and circuit VDB05 (WH) (HS-CAN -) shorted together
  8. PCM
  9. RCM
  10. Occupant classification sensor module
  11. 4WD control module
  12. Instrument cluster
  13. SJB

The ABS module communicates with the scan tool through circuit VDB10 (GY). Voltage for the ABS module is provided by circuits CBP20 (YE/VT), SBB17 (RD) and SBB15 (WH/RD). Circuits GD122 (BK) provide ground.

Possible Causes

  1. Fuse
  2. Circuit VDB10 (GY) open, short to ground or voltage
  3. Circuit CBP20 (YE/VT) open
  4. Circuit SBB15 (WH/RD) open
  5. Circuit SBB17 (RD) open
  6. Circuit GD122 (BK) open
  7. 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 module shares the HS-CAN with the powertrain control module (PCM), the four wheel drive (4WD) module, the occupant classification sensor module, the smart junction box (SJB), and the instrument cluster. Voltage for the RCM is provided by circuit CBP08 (GY/YE), and the RCM is case grounded.

Possible Causes

  1. Fuse
  2. Circuit VDB04 (WH/BU) open (HS-CAN +)
  3. Circuit VDB05 (WH) open (HS-CAN -)
  4. Circuit CBP08 (GY/YE) open
  5. Case ground open
  6. RCM

The SJB 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 SJB. The SJB shares the HS-CAN with the powertrain control module (PCM), the restraints control module (RCM), the occupant classification sensor module, the four wheel drive (4WD) control module, and the instrument cluster. Voltage is supplied through circuit SBB05 (GY/RD), and ground is provided through circuit GD174 (BK/WH).

Possible Causes

  1. Fuse
  2. Circuit SBB05 (GY/RD) open
  3. Circuit GD174 (BK/WH) open
  4. Circuit VDB04 (WH/BU) open (HS-CAN +)
  5. Circuit VDB05 (WH) open (HS-CAN -)
  6. SJB

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 network connection to the instrument cluster. The instrument cluster shares the HS-CAN with the powertrain control module (PCM), the restraints control module (RCM), the occupant classification sensor module, the four wheel drive (4WD) control module, and the smart junction box (SJB). Voltage is supplied by circuits SBP33 (RD), CBP09 (VT/GY) and CBP10 (YE/OG). Ground is supplied by circuits GD161 (BK/YE) and GD174 (BK/WH).

DTC U0002 (Instrument Cluster) - sets when there is a communication problem on the HS-CAN bus.

Possible Causes

  1. Fuse
  2. Circuit VDB04 (WH/BU) open (HS-CAN +)
  3. Circuit VDB05 (WH) open (HS-CAN -)
  4. Circuit SBP33 (RD) open
  5. Circuit CBP09 (VT/GY) open
  6. Circuit CBP10 (YE/OG) open
  7. Circuit GD161 (BK/YE) open
  8. Circuit GD174 (BK/WH) open
  9. Instrument cluster

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 restraints control module (RCM), the occupant classification sensor module, the instrument cluster, and the smart junction box (SJB). Voltage is supplied by circuits SBB27 (BU/RD), SBP28 (GN/RD) and CBP10 (YE/OG). Ground is supplied by circuits GD161 (BK/YE) and GD174 (BK/WH).

Possible Causes

  1. Fuse
  2. Circuit VDB04 (WH/BU) open (HS-CAN +)
  3. Circuit VDB05 (WH) open (HS-CAN -)
  4. Circuit CBP10 (YE/OG) open
  5. Circuit SBP28 (GN/RD) open
  6. Circuit SBB27 (BU/RD) open
  7. Circuit GD161 (BK/YE) open
  8. Circuit GD174 (BK/WH) open
  9. 4WD control module

The scan tool communicates with the ISO 9141 network through the data link connector (DLC). The generic electronic module (GEM) communicates with the scan tool through the ISO 9141 communications network, circuit 70 (LB/WH).

Possible Causes

  1. Circuit VDB10 (GY) open, short to ground or voltage
  2. DLC
  3. GEM

The scan tool is connected to the data link connector (DLC) to communicate with the high speed controller area network (HS-CAN) and International Standards Organization (ISO) 9141 communications networks.

Possible Causes

  1. Fuse
  2. Circuit SBP29 (GY/RD) open
  3. Circuit GD174 (BK/WH) open
  4. Circuit GD161 (BK/YE) open
  5. DLC
  6. Scan tool

Scheme 2

Scheme 2: PINPOINT TEST H: NO POWER TO THE SCAN TOOL
Scheme 2: PINPOINT TEST H: NO POWER TO THE SCAN TOOL
  1. H1 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 H2 . NO : REPAIR the DLC as necessary. CLEAR the DTCs. REPEAT the network test with the scan tool.
  2. H2 CHECK THE VOLTAGE TO THE DLC Measure the voltage between the DLC C251-16, circuit SBP29 (GY/RD), harness side and ground. Is the voltage greater than 10 volts? YES : Go to H3 . NO : VERIFY the smart junction box (SJB) fuse 29 (20A) is OK. If OK, REPAIR the circuit. CLEAR the DTCs. REPEAT the network test with the scan tool.
  3. H3 CHECK THE DLC GROUND CIRCUITS Measure the resistance between the DLC C251-4, circuit GD161 (BK/YE), harness side and ground; and between the DLC C251-5, circuit GD174 (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. CLEAR the DTCs. REPEAT the network test with the scan tool.

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