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Pinpoint Test B: The Occupant Classification System Module (OCSM) Does Not Communicate With the Scan Tool

WARNING: This page is about a different car, the 2008 Ford Ranger. However, it is still accessible from the selected car via links, so may be relevant.

Refer to appropriate SYSTEM WIRING DIAGRAMS article, Module Communications Network for schematic and connector information.

Refer to appropriate SYSTEM WIRING DIAGRAMS article, Supplemental Restraint System for schematic and connector information.

Normal Operation 

The OCSM 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 OCSM. The OCSM shares the HS-CAN with the PCM, the 4X4 control module, the restraints control module (RCM), the SJB, and the instrument cluster (IC). Voltage for the RCM is provided by circuit CBP08 (GY/YE) and circuit GD174 (BK/WH) provides ground.

This pinpoint test is intended to diagnose the following:

PINPOINT TEST B: THE OCCUPANT CLASSIFICATION SYSTEM MODULE (OCSM) DOES NOT COMMUNICATE WITH THE SCAN TOOL 

NOTE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
  1. B1 CHECK THE OCSM VOLTAGE SUPPLY CIRCUITS FOR AN OPEN 
    • Key in OFF position.
    • Disconnect: OCSM C3159
    • Key in ON position.
      • Fig 1: Measuring Voltage Between Occupant Classification Sensor Module C3159-1, Circuit CBP17 (BN/GN)
      GF0028106Courtesy of FORD MOTOR CO.
    • Measure the voltage between the OCSM C3159-1, circuit CBP08 (GY/YE), harness side and ground.
    • Is the voltage greater than 10 volts? 
    1. YES  : Go to  B2.
    2. NO  : VERIFY the SJB fuse 46 (7.5A) is OK. If OK, REPAIR the circuit. CLEAR the DTCs. REPEAT the network test with the scan tool.
  2. B2 CHECK THE GROUND CIRCUIT FOR AN OPEN 
    • Key in OFF position.
      • Fig 2: Measuring Resistance Between Occupant Classification Sensor Module C3159-14, Circuit GD145 (BK/BU)
      GF0028107Courtesy of FORD MOTOR CO.
    • Measure the resistance between the OCSM C3159-14, circuit GD174 (BK/WH), harness side and ground.
    • Is the resistance less than 5 ohms? 
    1. YES  : Go to  B3.
    2. NO  : REPAIR the circuit. CLEAR the DTCs. REPEAT the network test with the scan tool.
  3. B3 CHECK THE HS-CAN CIRCUITS BETWEEN THE DATA LINK CONNECTOR (DLC) AND THE OCSM FOR AN OPEN 
      Fig 3: Measuring Resistance
      GF0028108Courtesy of FORD MOTOR CO.
    • Measure the resistance between the OCSM C3159-18, circuit VDB04 (WH/BU), harness side and the DLC C251-6, circuit VDB04 (WH/BU), harness side.
      • Fig 4: Measuring Resistance
      GF0028109Courtesy of FORD MOTOR CO.
    • Measure the resistance between the OCSM C3159-9, circuit VDB05 (WH), harness side and the DLC C251-14, circuit VDB05 (WH), harness side.
    • Are the resistances less than 5 ohms? 
    1. YES  : Go to  B4.
    2. NO  : REPAIR the circuit in question. CLEAR the DTCs. REPEAT the network test with the scan tool.
  4. B4 CHECK FOR CORRECT OCSM OPERATION 
    • Disconnect the OCSM connector.
    • Check for:
      • corrosion
      • damaged pins
      • pushed-out pins
    • Connect the OCSM connector and make sure it seats correctly.
    • Operate the system and verify the concern is still present.
    • Is the concern still present? 
    1. YES  : INSTALL a new OCSM. REFER to SUPPLEMENTAL RESTRAINT SYSTEM article. REPEAT the network test with the scan tool.
    2. NO  : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the network test with the scan tool.
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