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Pinpoint Test C: The Restraints Control Module (RCM) 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 restraints control module (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 with the PCM, the accessory protocol interface module (APIM), the ABS module, the occupant classification system module (OCSM), the 4X4 control module (if equipped), the headlamp control module (HCM) (if equipped), the steering angle sensor module (SASM) (if equipped) and the instrument cluster (IC). Voltage for the RCM is provided by circuit CBP46 (WH/BU), and the RCM is case grounded.

This pinpoint test is intended to diagnose the following:

PINPOINT TEST C: THE RESTRAINTS CONTROL MODULE (RCM) DOES NOT RESPOND TO THE SCAN TOOL 

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.
WARNING: Never probe the electrical connectors on air bag, safety canopy or side air curtain modules. Failure to follow this instruction may result in the accidental deployment of these modules, 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.
  1. C1 CHECK THE RCM CONNECTION 
    • Key in OFF position.
    • Depower the SRS. Refer to SUPPLEMENTAL RESTRAINT SYSTEM article.
    • Disconnect: RCM C310a
    • Disconnect: RCM C310b
    • Are RCM C310a pin 12 and RCM C310b pins 17 and 18 OK? 
    1. YES  : Go to  C2.
    2. NO  : REPAIR the RCM connector pins as necessary. REPOWER the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM article. CLEAR the DTCs. REPEAT the network test with the scan tool.
  2. C2 CHECK THE RCM VOLTAGE SUPPLY CIRCUIT FOR AN OPEN 
    • 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
      G03881123Courtesy of FORD MOTOR CO.
    • Measure the voltage between the RCM C310a-12, circuit CBP46 (WH/BU), harness side and ground.
    • Is the voltage greater than 10 volts? 
    1. YES  : Go to  C3.
    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.
  3. C3 CHECK THE RCM CASE GROUND 
    • Key in OFF position.
    • Measure the resistance between the RCM case and a good chassis ground.
    • Is the resistance less than 5 ohms? 
    1. YES  : Go to  C4.
    2. NO  : REPAIR the RCM case ground as necessary. REACTIVATE the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM article. CLEAR the DTCs. REPEAT the network test with the scan tool.
  4. C4 CHECK THE HS-CAN CIRCUITS BETWEEN THE RCM AND THE DATA LINK CONNECTOR (DLC) FOR AN OPEN 
      Fig 2: Checking HS-CAN (+) Circuit
      GF0023530Courtesy of FORD MOTOR CO.
    • Measure the resistance between the RCM C310b-18, circuit VDB04 (WH/BU), harness side and the DLC C251-6, circuit VDB04 (WH/BU), harness side.
      • Fig 3: Checking HS-CAN (-) Circuit
      GF0023531Courtesy of FORD MOTOR CO.
    • Measure the resistance between the RCM C310b-17, 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  C5.
    2. NO  : REPAIR the circuit in question. REACTIVATE the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM article. CLEAR the DTCs. REPEAT the network test with the scan tool.
  5. C5 CHECK FOR CORRECT RCM OPERATION 
    • Disconnect all the RCM connectors.
    • Check for:
      • corrosion
      • damaged pins
      • pushed-out pins
    • Connect all the RCM connectors and make sure they seat correctly.
    • Operate the system and verify the concern is still present.
    • Is the concern still present? 
    1. YES  : INSTALL a new RCM. 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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