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Pinpoint Test K: The Restraints Control Module (RCM) Does Not Respond To The Scan Tool

WARNING: This page is about a different car, the 2009 Mercury Grand Marquis and 2009 Ford Crown Victoria. 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 restraints control module (RCM) communicates with the scan tool through the International Standards Organization (ISO) 9141 network. Circuit 70 (LB/WH) provides the network connection to the RCM. The RCM shares the ISO network with the fire suppression system module (FSSM) (if equipped). Voltage for the RCM is provided by circuit 937 (RD/WH). Circuit 676 (PK/OG) provides ground.

This pinpoint test is intended to diagnose the following:

PINPOINT TEST K: 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. K1 CHECK THE RCM VOLTAGE SUPPLY CIRCUIT FOR AN OPEN 
    • Key in OFF position.
    • Deactivate the SRS. Refer to SUPPLEMENTAL RESTRAINT SYSTEM article.
    • Disconnect: RCM C310a
    • Key in ON position.
      • Fig 1: Measuring Voltage
      G03881123Courtesy of FORD MOTOR CO.
    • Measure the voltage between the RCM C310a-12, circuit 937 (RD/WH), harness side and ground.
    • Is the voltage greater than 10 volts? 
    1. YES  : Go to  K2.
    2. NO  : VERIFY the central junction box (CJB) fuse 22 (10A) 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. K2 CHECK THE RCM GROUND CIRCUIT 
    • Key in OFF position.
    • Measure the resistance between the RCM C310a-16, circuit 676 (PK/OG), harness side and ground.
    • Is the resistance less than 0.5 ohms? 
    1. YES  : Go to  K3.
    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. K3 CHECK CIRCUIT 70 (LB/WH) BETWEEN THE RCM AND THE DATA LINK CONNECTOR (DLC) FOR AN OPEN 
      Fig 2: Checking Circuit For Open
      GF0004712Courtesy of FORD MOTOR CO.
    • Measure the resistance between the RCM C310a-11, circuit 70 (LB/WH), harness side and the DLC C251-7, circuit 70 (LB/WH), harness side.
    • Is the resistance less than 5 ohms? 
    1. YES  : Go to  K4.
    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.
  4. K4 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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