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Pinpoint Test AO: No Communication With The Restraints Control Module (RCM)

WARNING: This page is about a different car, the 2006 Mercury Montego, 2006 Ford Freestyle, and 2006 Ford Five Hundred. However, it is still accessible from the selected car via links, so may be relevant.
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. AO1 CHECK THE RCM C310b PIN 31 and 32 FOR DAMAGE 
    WARNING:
    1. Restraint system diagnostic tools are for service only. Tools must be removed prior to operating the vehicle over the road. Failure to remove restraint system diagnostic tools could result in injury and possible violation of vehicle safety standards.
    2. Do not handle, move or change the original horizontal mounting position of the restraints control module (RCM) while the RCM is connected and the ignition switch is ON. Failure to follow these instructions may result in the inadvertent deployment of the safety canopy and risk of personal injury.
    3. Never probe the connectors on the air bag module. Doing so can result in air bag deployment, which can result in personal injury.
    4. The safety belt pretensioner is a pyrotechnic device. Always wear safety glasses when repairing an air bag equipped vehicle and when handling a safety belt buckle pretensioner or safety belt retractor pretensioner. Never probe a pretensioner electrical connector. Doing so could result in pretensioner or air bag deployment and could result in personal injury.
    5. Never probe the electrical connector on a safety canopy module. Doing so can result in safety canopy deployment.
    NOTE:
    1. If a seat equipped with a supplemental restraint system (SRS) component is being serviced, the SRS must be depowered.
    2. After diagnosing or repairing an SRS, the restraint system diagnostic tools must be removed before operating the vehicle over the road. 
    3. The SRS must be fully operational and free of faults before releasing the vehicle to the customer.

    Yes:  GO to  AO2.

    No:  REPAIR RCM C310b or RCM C310b pin 31 and 32 as necessary. RETEST the communication to the RCM. RECONNECT the system. If previously directed to deactivate the system, REACTIVATE the system. REFER to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEACTIVATION AND REACTIVATION . REPOWER the system. REFER to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING . PROVE OUT the system. CLEAR all DTCs.

  2. AO2 CHECK DLC C251 PINS 6 AND 14 FOR DAMAGE 
    • Inspect DLC C251 and DLC C251 pins 6 and 14 for damage.
      Fig 1: Checking DLC C251 Pins 6 & 14 For Damage
      G04659556Courtesy of FORD MOTOR CO.
    • Are DLC C251 and DLC C251 pins 6 and 14 OK? 

    Yes:  GO to  AO3.

    No:  REPAIR DLC C251 or DLC C251 pins 6 and 14 as necessary. RETEST the communication to the RCM. RECONNECT the system. If previously directed to deactivate the system, REACTIVATE the system. REFER to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEACTIVATION AND REACTIVATION . REPOWER the system. REFER to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING . PROVE OUT the system. CLEAR all DTCs.

  3. AO3 CHECK THE IGNITION CIRCUIT 937 (RD/WH) FOR AN OPEN 
    • Key in OFF position.
    • Deactivate the system. REFER to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEACTIVATION AND REACTIVATION .
    • Key in ON position.
    • Measure the voltage between RCM C310a-12, circuit 937 (RD/WH), harness side and ground.
      Fig 2: Checking Ignition Circuit 937 (RD/WH) For Open
      G04659557Courtesy of FORD MOTOR CO.
    • Is the voltage between 8 and 18 volts? 

    Yes:  GO to  AO4.

    No:  VERIFY that smart junction box (SJB) fuse 21 (7.5A) is OK. If OK, REPAIR circuit 937 (RD/WH). RETEST the communication to the RCM. RECONNECT the system. If previously directed to deactivate the system, REACTIVATE the system. REFER to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEACTIVATION AND REACTIVATION . REPOWER the system. REFER to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING . PROVE OUT the system. CLEAR all DTCs.

  4. AO4 CHECK THE RCM CASE GROUND 
    • Key in OFF position.
    • Measure the resistance between the RCM case and a good sheet metal ground near the RCM.
    • Is the resistance less than 5 ohms? 

    Yes:  GO to  AO5.

    No:  REPAIR ground as necessary. RETEST the communication to the RCM. RECONNECT the system. If previously directed to deactivate the system, REACTIVATE the system. REFER to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEACTIVATION AND REACTIVATION . REPOWER the system. REFER to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING . PROVE OUT the system. CLEAR all DTCs.

  5. AO5 CHECK THE HS-CAN CIRCUITS BETWEEN THE RCM AND DLC C251 FOR AN OPEN 
    • Measure the resistance between RCM C310b-31, circuit 1908 (WH), harness side and DLC C251-6, circuit 1908 (WH), harness side; and between RCM C310b-32, circuit 1909 (BK), harness side and DLC C251-14, circuit 1909 (BK), harness side.
      Fig 3: Checking HS-CAN Circuits Between RCM & DLC C251 For Open
      G04659558Courtesy of FORD MOTOR CO.
    • Are the resistances less than 0.5 ohm? 

    Yes:  GO to  AO6.

    No:  REPAIR circuit 1908 (WH) or circuit 1909 (BK). RETEST the communication to the RCM. RECONNECT the system. If previously directed to deactivate the system, REACTIVATE the system. REFER to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEACTIVATION AND REACTIVATION . REPOWER the system. REFER to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING . PROVE OUT the system. CLEAR all DTCs.

  6. AO6 CONFIRM THE RCM FAULT 
    NOTE: Make sure all restraint system diagnostic tools, sensor electrical connectors and the RCM electrical connector are connected before carrying out the on-demand self test. If not, erroneous DTCs will be recorded.
    • Key in OFF position.
    • Connect: RCM C310a and C310b.
    • Enter the following diagnostic mode on the scan tool: On-Demand Self Test.
    • Did the diagnostic tool communicate with the RCM? 

    Yes:  Fault corrected. RECONNECT the system. If previously directed to deactivate the system, REACTIVATE the system. REFER to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEACTIVATION AND REACTIVATION . REPOWER the system. REFER to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING . PROVE OUT the system. CLEAR all DTCs.

    No:  INSTALL a new RCM. REFER to RESTRAINTS CONTROL MODULE (RCM) . RETEST the communication to the RCM. RECONNECT the system. If previously directed to deactivate the system, REACTIVATE the system. REFER to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEACTIVATION AND REACTIVATION . REPOWER the system. REFER to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING . PROVE OUT the system. CLEAR all DTCs.

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