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Home >> Mercury >> 2010 >> Milan Base, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 89 (Supplemental Inflatable Restraint System -- F250-F550 Super Duty) >> Diagnosis And Testing >> Pinpoint Tests - Air Bag Supplemental Restraint System (SRS) >> Pinpoint Test Q: LFC 35/DTC B1935 - Air Bag Passenger Inflator Circuit Resistance Low on Squib >> Pinpoint Test Q: LFC 35/DTC B1935 - Air Bag Passenger Inflator Circuit Resistance Low On Squib

Pinpoint Test Q: LFC 35/DTC B1935 - Air Bag Passenger Inflator Circuit Resistance Low On Squib

WARNING: This page is about a different car, the 2005 Ford Pickup, 2005 Ford F550 Super Duty, 2005 Ford F450 Super Duty, and 2005 Ford Cab & Chassis. 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. Q1 CHECK FOR ON-DEMAND AND CONTINUOUS DTCs 
    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.
    NOTE: After diagnosing or repairing a supplemental restraint system (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 diagnostic tool: Retrieve/Clear Continuous DTCs.
    • Enter the following diagnostic mode on the diagnostic tool: On-Demand Self Test.
    • Was DTC B1935 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 Q2.
    • No  : This is an intermittent fault. The fault condition is not present at this time. GO to  Q6.
  2. Q2 CHECK THE PASSENGER AIR BAG MODULE 
    • Yes  : GO to Q3.
    • No  : INSTALL a new passenger air bag module. REFER to PASSENGER AIR BAG MODULE  in this article. GO to  Q5.
  3. Q3 CHECK CIRCUIT 607 (LB/OG) AND CIRCUIT 616 (PK/BK) FOR LOW RESISTANCE BETWEEN THE PASSENGER AIR BAG MODULE AND RCM 
    • Key in OFF position.
    • Depower the system. Refer to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING  in this article.
    • Disconnect: Passenger Air Bag Restraint System Diagnostic Tool.
    • Measure the resistance between passenger air bag C256, circuit 607 (LB/OG), harness side and circuit 616 (PK/BK), harness side.
      Fig 1: Measuring Resistance Between Connector Terminals
      G03891306Courtesy of FORD MOTOR CO.
    • Is the resistance greater than 10,000 ohm? 
    • Yes  : GO to  Q5.
    • No  : GO to Q4.
  4. Q4 CHECK THE RCM 
    • Disconnect: RCM 2041.
    • Measure the resistance between RCM C2041 pin 6, circuit 607 (LB/OG), component side and RCM C2041 pin 4, circuit 616 (PK/BK), component side.
      Fig 2: Measuring Resistance Between RCM C2041 Pin 6 Circuit 607 (LB/OG), And RCM C2041 Pin 4 Circuit 616
      G03912059Courtesy of FORD MOTOR CO.
    • Is the resistance greater than 10,000 ohms? 
  5. Q5 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: Passenger Air Bag Module Restraint System Diagnostic Tool.
    • Connect: RCM C2041.
    • Repower the system. Do not  prove out the system at this time. Refer to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING  in this article.
    • Enter the following diagnostic mode on the diagnostic tool: On-Demand Self Test.
    • Was DTC B1935 retrieved during the on-demand self test? 
    • Yes  : INSTALL and CONFIGURE a new RCM. REFER to RESTRAINTS CONTROL MODULE (RCM)  in this article. GO to  Q7.
    • No  : CHECK for causes of the intermittent fault. ATTEMPT to recreate the hard fault by flexing the wire harness and cycling the ignition key frequently. ACTIVATE other systems in the same wire harness. REPAIR any intermittent concerns found. GO to  Q7.
  6. Q6 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 intermittent fault at or near the passenger air bag module connector. REPAIR any intermittent concerns found.

      If an intermittent concern was  found and repaired, GO to Q7.

      If an intermittent concern was not  found, GO to  Q3.

    • No  : CHECK for causes of intermittent low resistance 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 Q7.
  7. Q7 CHECK FOR ADDITIONAL DTCs 
    • Refer to the continuous DTCs recorded during Step  Q1.
    • Were any continuous DTCs retrieved during Step   Q1 ? 
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