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Home >> Ford >> 2005 >> Escape Base, 3.0 1, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 176 (Supplemental Inflatable Restraint System) >> Diagnosis And Testing >> Pinpoint Tests - Air Bag and Safety Belt Pretensioner Supplemental Restraint System (SRS) >> Pinpoint Test AC: LFC 16/DTC B2909 - Belt Tension Sensor Fault >> Testing

Pinpoint Test AC: LFC 16/DTC B2909 - Belt Tension Sensor Fault: Testing

WARNING: This page is about a different car, the 2005 Mercury Montego, 2005 Ford Freestyle, and 2005 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. AC1 CHECK FOR CONTINUOUS OR ON-DEMAND 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: 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.
    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.
    WARNING: Never probe the electrical connector on a safety canopy module. Doing so can result in safety canopy deployment.
    NOTE: If a seat equipped with a supplemental restraint system (SRS) component is being serviced, the SRS must be depowered.
    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: On-Demand Self Test.
    • Enter the following diagnostic mode on the scan tool: Flag DTC B2909/Record All Flagged Faults.
    • Enter the following diagnostic mode on the scan tool: Retrieve/Flag/Record Continuous DTCs.
    • Was DTC B2909 retrieved during the on-demand self test? 
    1. 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.

      Using the flagged faults recorded, GO to the appropriate PINPOINT TEST .

      If a flagged fault of "?  " was recorded, multiple faults exist and the entire pinpoint test must be carried out.

      For belt tension sensor with a circuit fault (FPTS_F), GO to AC2.

      For belt tension sensor with a short to ground fault (FPTS_SG), GO to  AC4.

    2. No  : This is an intermittent fault. The fault condition is not present at this time. GO to  AC9.
  2. AC2 CHECK THE BELT TENSION SENSOR CIRCUITS FOR A SHORT TO VOLTAGE 
    • Key in OFF position.
    • Depower the system. Refer to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING .
    • Disconnect: Passenger Seat Side Air Bag Module C3227 (Vehicles with seat side air bag modules).
    • Connect: Restraint System Diagnostic Tool 418-F395 to Passenger Seat Side Air Bag Module C3227 (Vehicles with seat side air bag modules).
    • Disconnect: Belt Tension Sensor C3238.
    • Disconnect: OCS ECU C3159.
    • Repower the system. Do not  prove out the system at this time. Refer to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING .
    • Key in ON position.
    • Measure the voltage between the OCS ECU C3159 pin B, circuit 2088 (TN/RD), harness side and ground; pin C, circuit 2090 (DB/OG), harness side and ground; pin A, circuit 2089 (OG/BK), harness side and ground.
      Fig 1: Measuring Voltage Between OCS ECU C3159 Pin B, Circuit 2088 Harness Side And Ground
      G03903756Courtesy of FORD MOTOR CO.
    • Are the voltages less than 0.2 volt? 
    1. Yes  : GO to AC3.
    2. No  : REPAIR circuit 2088 (TN/RD), circuit 2089 (OG/BK) or circuit 2090 (DB/OG). GO to  AC10.
  3. AC3 CHECK BELT TENSION SENSOR CIRCUITS FOR OPEN 
    • Key in OFF position.
    • Depower the system. Refer to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING .
    • Measure the resistance between OCS C3159 pin B, circuit 2088 (TN/RD), harness side and the belt tension sensor C3238 pin 1, circuit 2088 (TN/RD), harness side; and between OCS C3159 pin C, circuit 2090 (DB/OG), harness side and the belt tension sensor C3238 pin 2, circuit 2090 (DB/OG), harness side; and between the OCS C3159 pin A, circuit 2089 (OG/BK), harness side and the belt tension sensor C3238 pin 3, circuit 2089 (OG/BK), harness side.
      Fig 2: Measuring Resistance Between OCS C3159 Pin B Harness Side And Ground
      G03959542Courtesy of FORD MOTOR CO.
    • Are the resistances less than 0.5 ohm? 
    1. Yes  : GO to  AC5.
    2. No  : REPAIR circuit 2088 (TN/RD), circuit 2089 (OG/BK) or circuit 2090 (DB/OG).

      GO to  AC10.

  4. AC4 CHECK CIRCUITS 2088 (TN/RD), 2089 (OG/BK) and 2090 (DB/OG) FOR A SHORT TO GROUND 
    • Key in OFF position.
    • Depower the system. Refer to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING .
    • Measure the resistance between OCS ECU C3159 pin B, circuit 2088 (TN/RD), harness side and ground; and between OCS ECU C3159 pin A, circuit 2089 (OG/BK) harness side and ground; and between OCS ECU C3159 pin C, circuit 2090 (DB/OG), harness side and ground.
      Fig 3: Measuring Resistance Between OCS ECU C3159 Pin B, Circuit 2088 (TN/RD), Harness Side And Ground
      G03903760Courtesy of FORD MOTOR CO.
    • Are the resistances greater than 10,0000 ohms? 
    1. Yes  : GO to AC5.
    2. No  : REPAIR circuit 2088 (TN/RD), circuit 2089 (OG/BK) or circuit 2090 (DB/OG) : GO to  AC10.
  5. AC5 CHECK CIRCUITS 2088 (TN/RD), 2089 (OG/BK) AND 2090 (DB/OG) FOR A SHORT 
    • Measure the resistance between the OCS ECU C3159:
      • pin B, circuit 2088 (TN/RD), harness side and pin A, circuit 2089 (OG/BK), harness side.
      • pin B, circuit 2088 (TN/RD), harness side and pin C, circuit 2090 (DB/OG), harness side.
      • pin A, circuit 2089 (OG/BK), harness side and pin C, circuit 1203 (BK/LB), harness side.
        Fig 4: Checking Circuits For Short
        G03903762Courtesy of FORD MOTOR CO.
    • Are the resistances greater than 10,0000 ohms? 
    1. Yes  : GO to AC6.
    2. No  : REPAIR circuit 2088 (TN/RD), circuit 2090 (DB/OG) or circuit 2089 (OG/BK). GO to  AC10.
  6. AC6 CHECK OCS ECU OUTPUT 
    • Connect: OCS ECU C3159.
    • Repower the system. Do not  prove out the system at this time. Refer to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING .
    • Key in ON position.
    • Measure the voltage between belt tension sensor C3238 pin 1, circuit 2088 (TN/RD), harness side and pin 2, circuit 2090 (DB/OG), harness side.
      Fig 5: Measuring Voltage Between Belt Tension Sensor C3238 Pin 1, Circuit 2088 (TN/RD), Harness Side And Pin
      G03959545Courtesy of FORD MOTOR CO.
    • Is the voltage approximately 5 volts? 
    1. Yes  : GO to AC7.
    2. No  : INSTALL a new OCS service kit. REFER to OCCUPANT CLASSIFICATION SENSOR - SERVICE KIT . GO to  AC10.
  7. AC7 CHECK BELT TENSION SENSOR VOLTAGE OUTPUT 
    • Key in OFF position.
    • Depower the system. Refer to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING .
    • Fig 6: Checking Belt Tension Sensor Voltage Output
      G03966666Courtesy of FORD MOTOR CO.
    • Connect a fused jumper lead between the belt tension sensor C3238 pin 1, circuit 2088 (TN/RD), harness side and pin 1, circuit 2088 (TN/RD), component side.
    • Connect a fused jumper lead between the belt tension sensor C3238 pin 2, circuit 2090 (DB/OG), harness side and pin 2, circuit 2090 (DB/OG), component side.
    • Repower the system. Do not  prove out the system at this time. Refer to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING .
    • Key in ON position.
    • Measure the voltage between the belt tension sensor C3238 pin 3, circuit 2089 (OG/BK), component side and ground as you vary the tension of the belt tension sensor.
    • Does the voltage vary from approximately 0.95 volt with no tension applied to the sensor to approximately 3.8 volts with full tension applied to the sensor? 
    1. Yes  : GO to AC8.
    2. No  : INSTALL a new belt tension sensor. REFER to SAFETY BELT SYSTEM . GO to  AC10.
  8. AC8 CONFIRM THE BELT TENSION SENSOR 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.
    1. Yes  : INSTALL a new OCS service kit. REFER to OCCUPANT CLASSIFICATION SENSOR - SERVICE KIT . GO to  AC10.
    2. 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  AC10.
  9. AC9 CHECK FOR AN INTERMITTENT FAULT 
    • Key in OFF position.
    • Enter the following diagnostic mode on the scan tool: On-Demand Self Test.
    • Enter the following diagnostic mode on the scan tool: Flag DTC B2909/Record All Flagged Faults.
    • Was DTC B2909 retrieved during the on-demand self test? 
    1. 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.

      Using the flagged faults recorded, GO to the appropriate PINPOINT TEST .

      If a flagged fault of "?  " was recorded, multiple faults exist and the entire pinpoint test must be carried out.

      For belt tension sensor with a circuit fault (FPTS_F), GO to  AC2.

      For belt tension sensor with a short to ground fault (FPTS_SG), GO to  AC4.

    2. 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 AC10.
  10. AC10 CHECK FOR ADDITIONAL DTCs 
    • Refer to the continuous DTCs recorded during Step  AC1.
    • Were any continuous DTCs retrieved during Step   AC1 ? 
    1. Yes  : Do not clear any DTCs until all DTCs have been resolved. GO to the RESTRAINTS CONTROL MODULE (RCM) DIAGNOSTIC TROUBLE CODE (DTC) TABLE  for pinpoint test direction.
    2. No  : 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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