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Home >> Ford >> 2000 >> Contour SE, 2.5 L, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 794 (Supplemental Restraint System) >> Diagnosis And Testing >> Pinpoint Tests - Air Bag and Safety Belt Pretensioner Supplemental Restraint System (SRS) >> Pinpoint Test T: LFC 21/DTC B1938 - Passenger Air Bag Circuit Shorted to Ground >> Pinpoint Test T: LFC 21/DTC B1938 - Passenger Air Bag Circuit Shorted To Ground

Pinpoint Test T: LFC 21/DTC B1938 - Passenger Air Bag Circuit Shorted To Ground

WARNING: This page is about a different car, the 2005 Ford RV Cutaway, 2005 Ford Econoline, 2005 Ford E450 Super Duty, and 2005 Ford Cutaway. 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 thorough Inspection and Verification  before proceeding with the Pinpoint Test.
  1. T1 CHECK FOR A HARD OR INTERMITTENT DTC 
    WARNING: 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.
    WARNING: Never probe the connectors on the air bag module. Doing so can result in air bag deployment, which can result in personal injury.
    WARNING: 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.
    CAUTION: To avoid potential damage to the restraints control module (RCM), make sure the RCM and bracket assembly is secured to the floor pan and the SRS is depowered before either disconnecting or reconnecting the RCM electrical connectors.
    NOTE: After diagnosing or repairing an SRS, the restraint system diagnostic tools must be removed before operating the vehicle over the road.
    NOTE: The SRS must be fully operational and free of faults before releasing the vehicle to the customer.
    • Enter the following diagnostic mode on the scan tool: Retrieve/Record Continuous DTCs.
    • Enter the following diagnostic mode on the scan tool: On-Demand Self Test.
    • Was DTC B1938 retrieved during the on-demand self test? 
    • Yes  : This is a hard fault. The fault condition is still present. This fault cannot be cleared until it is corrected and the DTC is no longer retrieved during the on-demand self test. GO to T2.
    • No  : This is an intermittent fault. The fault condition is not present at this time. GO to  T5.
  2. T2 CHECK THE PASSENGER AIR BAG MODULE 
  3. T3 CHECK THE PASSENGER AIR BAG MODULE CIRCUITS 
    • Key in OFF position.
    • Depower the system. Refer to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING .
    • Disconnect: RCM C310a.
    • Disconnect: Passenger Air Bag Module Restraint System Diagnostic Tool.
    • Measure the resistance between RCM C310a pin 3, circuit 607 (LB/OG), harness side and ground; and between RCM C310a pin 4, circuit 616 (PK/BK), harness side and ground.
      Fig 1: Measuring Resistance Between RCM Pin 3 And Ground
      G03881003Courtesy of FORD MOTOR CO.
    • Are the resistances greater than 10,000 ohms? 
    • Yes  : GO to T4.
    • No  : Due to the shorting bar feature in the electrical connector, the fault can exist in either circuit. Do not remove or defeat the shorting bar.

    REPAIR circuit 607 (LB/OG) or circuit 616 (PK/BK). GO to  T6.

  4. T4 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.
    • Connect: RCM C310a.
    • Connect: Passenger Air Bag Module Restraint Diagnostic System Tool.
    • Repower the system. Do not  prove out the system at this time. Refer to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING .
    • Enter the following diagnostic mode on the scan tool: On-Demand Self Test.
    • Was DTC B1938 retrieved during the on-demand self test? 
    • Yes  : INSTALL a new RCM. REFER to RESTRAINTS CONTROL MODULE (RCM) . GO to  T6.
    • No  : CHECK for causes of intermittent short to ground on circuit 614 (GY/OG), circuit 615 (GY/WH), and the clockspring assembly. ATTEMPT to recreate the hard fault by flexing the wire harness and cycling the ignition key frequently. REPAIR any intermittent concerns found. GO to  T6.
  5. T5 CHECK FOR AN INTERMITTENT FAULT 
    • Yes  : This is a hard fault. The fault condition is now present. This fault cannot be cleared until it is corrected and the DTC is no longer retrieved during the on-demand self test.

      CHECK for causes of the intermittent fault at or near the affected air bag module connector. REPAIR any intermittent concerns found.

      If an intermittent concern was  found and repaired, GO to T6.

      If an intermittent concern was not  found and repaired, GO to  T3.

    • No  : CHECK for causes of intermittent short to ground on circuit 607 (LB/OG) and circuit 616 (PK/BK). ATTEMPT to recreate the hard fault by flexing the wire harness and cycling the ignition key frequently. REPAIR any intermittent concerns found. GO to T6.
  6. T6 CHECK FOR ADDITIONAL DTCs 
    • Refer to the continuous DTCs recorded during Step  T1.
    • Were any continuous DTCs retrieved during Step   T1  ? 
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