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Home >> Lincoln >> 2010 >> MKZ AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 937 (Supplemental Inflatable Restraint System) >> Diagnostic Tests >> Pinpoint Tests - Air Bag and Safety Belt Pretensioner Supplemental Restraint System (SRS) >> Pinpoint Tests >> Pinpoint Test U: LFC 16/DTC B2909 - Belt Tension Sensor Fault >> Pinpoint Test U: LFC 16/DTC B2909 - Belt Tension Sensor Fault

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

WARNING: This page is about a different car, the 2007 Mercury Mariner and 2007 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.
CAUTION: When installing a new restraints control module (RCM), always make sure the correct RCM is being installed. The RCM 40-pin connector is keyed differently for vehicles with safety canopies and side air bags than the 40-pin connector for vehicles without safety canopies and side air bags. Do not force the 40-pin connector onto the RCM. If the connector is forced onto the RCM, damage to the RCM and/or connector will occur.
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. U1 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 diagnostic tool: On-Demand Self Test/Retrieve and Record Continuous Memory DTCs
    • Enter the following diagnostic mode on the diagnostic tool: View and Record DTC B2909 Fault PIDs
    • Was on-demand DTC B2909 retrieved? 
    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 fault PIDs recorded, go to the appropriate pinpoint test step.

      For belt tension sensor with a circuit fault, go to  U2 .

      For belt tension sensor with a short to ground fault, go to  U4 .

    2. NO  : This is an intermittent fault when present as a continuous memory DTC only (DTC not retrieved on demand). The fault condition is not present at this time. Go to  U9 .
  2. U2 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: Belt Tension Sensor C3282
    • Disconnect: OCS ECU C3285
    • 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.
      • Fig 1: Checking Circuit For Voltage
      GF0002198Courtesy of FORD MOTOR CO.
    • Measure the voltage between the OCS ECU C3285-11, circuit 2088 (TN/RD), harness side and ground; C3285-13, circuit 1203 (BK/LB), harness side and ground; C3285-12, circuit 2089 (OG/BK), harness side and ground.
    • Are the voltages less than 0.2 volt? 
    1. YES  : Go to  U3.
    2. NO  : REPAIR circuit 2088 (TN/RD), circuit 2089 (OG/BK) or circuit 1203 (BK/LB). Go to  U10 .
  3. U3 CHECK BELT TENSION SENSOR CIRCUITS FOR OPEN 
    • Key in OFF position.
    • Depower the system. Refer to Supplemental Restraint System (SRS) Depowering and Repowering .
      • Fig 2: Checking Circuits For Open
      GF0016846Courtesy of FORD MOTOR CO.
    • Measure the resistance between OCS C3285-11, circuit 2088 (TN/RD), harness side and the belt tension sensor C3282-1, circuit 2088 (TN/RD), harness side; and between OCS C3285-13, circuit 1203 (BK/LB), harness side and the belt tension sensor C3282-2, circuit 1203 (BK/LB), harness side; and between the OCS C3285-12, circuit 2089 (OG/BK), harness side and the belt tension sensor C3282-3, circuit 2089 (OG/BK), harness side.
    • Are the resistances less than 0.5 ohm? 
    1. YES  : Go to  U5.
    2. NO  : REPAIR circuit 2088 (TN/RD), circuit 2089 (OG/BK) or circuit 1203 (BK/LB).

      Go to  U10.

  4. U4 CHECK CIRCUITS 2088 (TN/RD), 2089 (OG/BK) and 1203 (BK/LB) FOR A SHORT TO GROUND 
    • Key in OFF position.
    • Depower the system. Refer to Supplemental Restraint System (SRS) Depowering and Repowering .
      • Fig 3: Checking Circuits For Short To Ground
      GF0002200Courtesy of FORD MOTOR CO.
    • Measure the resistance between OCS ECU C3285-11, circuit 2088 (TN/RD), harness side and ground; and between OCS ECU C3285-12, circuit 2089 (OG/BK) harness side and ground; and between OCS ECU C3285-13, circuit 1203 (BK/LB), harness side and ground.
    • Are the resistances greater than 10,0000 ohms? 
    1. YES  : Go to  U5.
    2. NO  : REPAIR circuit 2088 (TN/RD), circuit 2089 (OG/BK) or circuit 1203 (BK/LB). Go to  U10 .
  5. U5 CHECK CIRCUITS 2088 (TN/RD), 2089 (OG/BK) AND 1203 (BK/LB) FOR A SHORT 
      Fig 4: Checking Circuits For Short Together
      GF0002201Courtesy of FORD MOTOR CO.
    • Measure the resistance between OCS ECU:
      • C3285-11, circuit 2088 (TN/RD), harness side and C3285-12, circuit 2089 (OG/BK), harness side.
      • C3285-11, circuit 2088 (TN/RD), harness side and C3285-13, circuit 1203 (BK/LB), harness side.
      • C3285-12, circuit 2089 (OG/BK), harness side and pin C3285-13, circuit 1203 (BK/LB), harness side.
    • Are the resistances greater than 10,0000 ohms? 
    1. YES  : Go to  U6.
    2. NO  : REPAIR circuit 2088 (TN/RD), circuit 1203 (BK/LB) or circuit 2089 (OG/BK). Go to  U10 .
  6. U6 CHECK OCS ECU OUTPUT 
    • Connect: OCS ECU C3285
    • 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.
      • Fig 5: Checking Circuit For Voltage
      GF0023973Courtesy of FORD MOTOR CO.
    • Measure the voltage between belt tension sensor C3282-1, circuit 2088 (TN/RD), harness side and C3282-2, circuit 1203 (BK/LB), harness side.
    • Is the voltage approximately 5 volts? 
    1. YES  : Go to  U7.
    2. NO  : INSTALL a new OCS service kit. REFER to Occupant Classification Sensor - Service Kit . Go to  U10 .
  7. U7 CHECK BELT TENSION SENSOR VOLTAGE OUTPUT 
    • Key in OFF position.
    • Depower the system. Refer to Supplemental Restraint System (SRS) Depowering and Repowering .
    • Connect a fused jumper lead between the belt tension sensor C3282 pin 1, circuit 2088 (TN/RD), harness side and C3282 pin 1, circuit 2088 (TN/RD), component side.
    • Connect a fused jumper lead between the belt tension sensor C3282 pin 2, circuit 1203 (BK/LB), harness side and C3282 pin 2, circuit 1203 (BK/LB), 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.
      • Fig 6: Checking Circuit For Voltage
      GF0023974Courtesy of FORD MOTOR CO.
    • Measure the voltage between the belt tension sensor C3282 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  U8.
    2. NO  : INSTALL a new belt tension sensor. REFER to SAFETY BELT SYSTEM article. Go to  U10 .
  8. U8 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  U10 .
    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  U10 .
  9. U9 CHECK FOR AN INTERMITTENT FAULT 
    • Key in OFF position.
    • Enter the following diagnostic mode on the diagnostic tool: On-Demand Self Test/Retrieve and Record Continuous Memory DTCs
    • Enter the following diagnostic mode on the diagnostic tool: View and Record DTC B2909 Fault PIDs
    • Was on-demand DTC B2909 retrieved? 
    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.

      Use the fault PIDs recorded and Go to the appropriate pinpoint test step.

      For belt tension sensor with a circuit fault, go to  U2 .

      For belt tension sensor with a short to ground fault, go to  U4 .

    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  U10 .
  10. U10 CHECK FOR ADDITIONAL DTCs 
    • Refer to the continuous memory DTCs recorded during Step U1.
    • Were any continuous memory DTCs retrieved during Step U1? 
    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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