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Pinpoint Test E: The Occupant Classification System Module (OCSM) Does Not Respond To The Scan Tool

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 occupant classification system module (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 accessory protocol interface module (APIM), the ABS module, the 4X4 control module (if equipped), the restraints control module (RCM), the headlamp control module (HCM) (if equipped), the steering angle sensor module (SASM) (if equipped) and the instrument cluster (IC). Voltage to the OCSM is supplied by circuit CBP46 (WH/BU). Ground is supplied by circuit GD143 (BK/VT).

This pinpoint test is intended to diagnose the following:

PINPOINT TEST E: THE OCCUPANT CLASSIFICATION SYSTEM MODULE (OCSM) DOES NOT RESPOND TO 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. E1 CHECK THE OCSM VOLTAGE SUPPLY CIRCUIT FOR AN OPEN 
    WARNING: Never probe the electrical connectors on safety belt buckle/retractor pretensioners or adaptive load limiting retractors. Failure to follow this instruction may result in the accidental deployment of the safety belt pretensioners or adaptive load limiting retractors, which increases the risk of serious personal injury or death.
    NOTE: The supplemental restraint system (SRS) must be fully operational and free of faults before releasing the vehicle to the customer.
    NOTE: Most faults are due to connector and/or wiring concerns. Carry out a thorough inspection and verification before proceeding with the pinpoint test.
    • Key in OFF position.
    • Depower the SRS. Refer to SUPPLEMENTAL RESTRAINT SYSTEM article.
    • Disconnect: OCSM C3159
    • Deactivate the SRS. Refer to SUPPLEMENTAL RESTRAINT SYSTEM article.
    • Repower the SRS. Refer to SUPPLEMENTAL RESTRAINT SYSTEM article.
    • Key in ON position.
      • Fig 1: Measuring Voltage Between Occupant Classification Sensor Module C3159-1, Circuit CBP46 (WH/BU)
      GF0032345Courtesy of FORD MOTOR CO.
    • Measure the voltage between the OCSM C3159-1, circuit CBP46 (WH/BU), harness side and ground.
    • Is the voltage greater than 10 volts? 
    1. YES  : Go to  E2.
    2. NO  : VERIFY the smart junction box (SJB) fuse 46 (7.5A) is OK. If OK, REPAIR the circuit. REACTIVATE the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM article. CLEAR the DTCs. REPEAT the network test with the scan tool.
  2. E2 CHECK THE OCSM GROUND CIRCUIT FOR AN OPEN 
    • Key in OFF position.
      • Fig 2: Measuring Resistance Between Occupant Classification Sensor Module C3159-14, Circuit GD143 (BK/VT)
      GF0032346Courtesy of FORD MOTOR CO.
    • Measure the resistance between the OCSM C3159-14, circuit GD143 (BK/VT), harness side and ground.
    • Is the resistance less than 5 ohms? 
    1. YES  : Go to  E3.
    2. NO  : REPAIR the circuit. REACTIVATE the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM article. CLEAR the DTCs. REPEAT the network test with the scan tool.
  3. E3 CHECK THE HS-CAN CIRCUITS BETWEEN THE OCSM AND THE DATA LINK CONNECTOR (DLC) 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  E4.
    2. NO  : REPAIR the circuit. CLEAR the DTCs. REPEAT the network test with the scan tool.
  4. E4 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.
    • Verify the concern is still present.
    • Is the concern still present? 
    1. YES  : INSTALL a new OCSM. REACTIVATE the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM article. CLEAR the DTCs. 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. REACTIVATE the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM article. CLEAR the DTCs. REPEAT the network test with the scan tool.
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