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B2909




Air Bag and Safety Belt Pretensioner Supplemental Restraint System (SRS)

Pinpoint Test AP: DTC B2909

Refer to Wiring Diagram Set 46, Supplemental Restraint System for schematic and connector information. Diagrams By Number

Normal Operation

The Belt Tension Sensor (BTS) operates in conjunction with the Occupant Classification System (OCS) system. The OCS (Occupant Classification System) system interprets a variable voltage signal provided by the BTS (Belt Tension Sensor) to identify the possible presence of a child safety seat in the front passenger seat. The voltage output of the BTS (Belt Tension Sensor) is proportional to the amount of tension applied to the sensor by the belt, no-tension low voltage (approximately 0.95 volt), high-tension high voltage (approximately 3.8 volts).

The Occupant Classification System Module (OCSM) monitors the BTS (Belt Tension Sensor) and all circuitry for faults. If a fault is detected, the OCSM (Occupant Classification System Module) will store DTC B2909 in memory and send a message to the Restraints Control Module (RCM). The RCM (Restraints Control Module) will store DTC B00A0:09 in memory and send a message to the Instrument Panel Cluster (IPC) module to illuminate the air bag warning indicator.





a Fault PIDs that end in OD indicate on-demand status and are associated with DTC B2909. Fault PIDs that end in CM indicate continuous memory status and are associated with DTC B2909.

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors

- BTS (Belt Tension Sensor) (part of RH front safety belt retractor)

- OCSM (Occupant Classification System Module)

PINPOINT TEST AP : DTC B2909

WARNING: Never probe the electrical connectors on air bag, Safety Canopy(R) or side air curtain modules. Failure to follow this instruction may result in the accidental deployment of these modules, which increases the risk of serious personal injury or death.

WARNING: Never disassemble or tamper with safety belt buckle/retractor pretensioners, adaptive load limiting retractors, safety belt inflators, or probe the electrical connectors. Failure to follow this instruction may result in the accidental deployment of the safety belt pretensioners, adaptive load limiting retractors, or safety belt inflators, which increases the risk of serious personal injury or death.

NOTICE: Use the correct probe adapter(s) from the Flex Probe Kit when taking measurements. Failure to use the correct probe adapter(s) may damage the connector.

Most faults are due to connector and/or wiring concerns. Carry out a thorough inspection and verification before proceeding with the pinpoint test. Inspection and Verification

NOTE: Supplemental Restraint System (SRS) components should only be disconnected or reconnected when instructed to do so within a pinpoint test step. Failure to follow this instruction may result in incorrect diagnosis of the SRS (Supplemental Restraint System).

NOTE: Always make sure the correct SRS (Supplemental Restraint System) component is being installed. Parts released for other vehicles may not be compatible even if they appear physically similar.
Check the part number listed in the Ford Catalog Advantage(TM) or equivalent to make sure the correct component is being installed. If an incorrect SRS (Supplemental Restraint System) component is installed, DTCs may set.

NOTE: The SRS (Supplemental Restraint System) must be fully operational and free of faults before releasing the vehicle to the customer.

AP1 RETRIEVE OCSM (Occupant Classification System Module) DTCs

- Ignition ON.

- Enter the following diagnostic mode on the scan tool: Self Test- OCSM (Occupant Classification System Module).

- Enter the following diagnostic mode on the scan tool: DataLogger- OCSM (Occupant Classification System Module)- View and Record All 2909 Fault PIDs.

- NOTE: Fault PIDs are only displayed in the DataLogger screen. The DTC status shown in the Self Test screen isNot a fault PID and must not be used for diagnostic navigation in this test.
Refer to PID list in Normal Operation to view 2909 fault PIDs.

Do any on-demand 2909 fault PIDs indicate a fault?

Yes
This fault cannot be cleared until it is corrected and the DTC is no longer retrieved on-demand during self-test.

For fault PID 2909_31_OD, GO to AP2.

For fault PID 2909_28_OD, GO to AP8.

For fault PID 2909_30_OD, GO to AP9.

For fault PID 2909_29_OD, GO to AP10.

No
This is an intermittent fault when present as a Continuous Memory Diagnostic Trouble Code (CMDTC) only. GO to AP14.

AP2 CHECK BTS (Belt Tension Sensor) CIRCUITS FOR A SHORT TO VOLTAGE

- Ignition OFF.

- Depower the SRS (Supplemental Restraint System). Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.

- Disconnect: Passenger Seat Side Air Bag Module C339.

- Disconnect: BTS (Belt Tension Sensor) C3238.

- Disconnect: OCSM (Occupant Classification System Module) C3159.

- Repower the SRS (Supplemental Restraint System). Do not prove out the SRS (Supplemental Restraint System) at this time. Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.

- Ignition ON.

- Measure the voltage between OCSM (Occupant Classification System Module) :
- C3159-11, circuit LR142 (YE/BU), harness side and ground.

- C3159-12, circuit VR210 (BU/BN), harness side and ground.






Is voltage present on either circuit?

Yes
REPAIR circuit LR142 (YE/BU) or VR210 (BU/BN). GO to AP15.

No
GO to AP3.

AP3 CHECK BTS (Belt Tension Sensor) CIRCUITS FOR AN OPEN

- Ignition OFF.

- Measure the resistance between OCSM (Occupant Classification System Module) C3159, harness side and BTS (Belt Tension Sensor) C3238, harness side using the following chart.









Are the resistances less than 0.5 ohm?

Yes
GO to AP4.

No
REPAIR circuit LR142 (YE/BU), GD901 (BK) or VR210 (BU/BN).

GO to AP15.

AP4 CHECK BTS (Belt Tension Sensor) VREF AND SIGNAL CIRCUITS FOR A SHORT TO GROUND

- Measure the resistance between OCSM (Occupant Classification System Module) :
- C3159-11, circuit LR142 (YE/BU), harness side and ground.

- C3159-12, circuit VR210 (BU/BN), harness side and ground.






Are the resistances greater than 10,000 ohms?

Yes
GO to AP5.

No
REPAIR circuit LR142 (YE/BU) or VR210 (BU/BN). GO to AP15.

AP5 CHECK FOR A SHORT BETWEEN BTS (Belt Tension Sensor) CIRCUITS

- Measure the resistance between BTS (Belt Tension Sensor) :
- C3238-1, circuit VR210 (BU/BN), harness side and C3238-3, circuit LR142 (YE/BU), harness side.

- C3238-1, circuit VR210 (BU/BN), harness side and C3238-2, circuit GD901 (BK), harness side.

- C3238-3, circuit LR142 (YE/BU), harness side and C3238-2, circuit GD901 (BK), harness side.






Are the resistances greater than 10,000 ohms?

Yes
GO to AP6.

No
REPAIR the affected circuits. GO to AP11.

AP6 CHECK OCSM (Occupant Classification System Module) OUTPUT

- Connect: OCSM (Occupant Classification System Module) C3159.

- Ignition ON.

- Measure the voltage between BTS (Belt Tension Sensor) C3238-3, circuit LR142 (YE/BU), harness side and C3238-2, circuit GD901 (BK), harness side.





Is the voltage approximately 5 volts?

Yes
GO to AP7.

No
INSTALL a new OCS (Occupant Classification System) system service kit. REFER to Occupant Classification Sensor . GO to AP15.

AP7 CHECK BTS (Belt Tension Sensor) VOLTAGE OUTPUT

- Ignition OFF.

- Connect a fused jumper wire between BTS (Belt Tension Sensor) C3238 pin 3, circuit LR142 (YE/BU), harness side and pin 3, circuit LR142 (YE/BU), component side.

- Connect a fused jumper wire between BTS (Belt Tension Sensor) C3238 pin 2, circuit GD901 (BK), harness side and pin 2, circuit GD901 (BK), component side.

- Ignition ON.

- Measure the voltage between BTS (Belt Tension Sensor) C3238 pin 1, component side and ground as the tension of the BTS (Belt Tension Sensor) varies by pulling upward at the safety belt webbing.





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?

Yes
INSTALL a new OCS (Occupant Classification System) system service kit. REFER to Occupant Classification Sensor . GO to AP15.

No
INSTALL a new RH safety belt retractor assembly. GO to AP15.

AP8 CHECK BTS (Belt Tension Sensor) CIRCUITS FOR A SHORT TO VOLTAGE

- Ignition OFF.

- Depower the SRS (Supplemental Restraint System). Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.

- Disconnect: Passenger Seat Side Air Bag Module C339.

- Disconnect: BTS (Belt Tension Sensor) C3238.

- Disconnect: OCSM (Occupant Classification System Module) C3159.

- Repower the SRS (Supplemental Restraint System). Do not prove out the system at this time. Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.

- Ignition ON.

- Measure the voltage between BTS (Belt Tension Sensor) :
- C3238-1, circuit VR210 (BU/BN), harness side and ground.

- C3238-3, circuit LR142 (YE/BU), harness side and ground.






Is any voltage present on either circuit?

Yes
REPAIR circuit VR210 (BU/BN) or LR142 (YE/BU). GO to AP15.

No
GO to AP13.

AP9 CHECK BTS (Belt Tension Sensor) CIRCUIT FOR AN OPEN

- Ignition OFF.

WARNING: Turn the ignition OFF and wait one minute to deplete the backup power supply. Failure to follow this instruction may result in serious personal injury or death in the event of an accidental deployment.

- Disconnect: BTS (Belt Tension Sensor) C3238.

- Disconnect: OCSM (Occupant Classification System Module) C3159.

- Measure the resistance between OCSM (Occupant Classification System Module) C3159, harness side and BTS (Belt Tension Sensor) C3238, harness side using the following chart.









Are the resistances less than 0.5 ohm?

Yes
GO to AP11.

No
REPAIR circuit VR210 (BU/BN), VR142 (YE/BU) or GD901 (BK). GO to AP15.

AP10 CHECK BTS (Belt Tension Sensor) CIRCUITS FOR A SHORT TO GROUND

- Ignition OFF.

WARNING: Turn the ignition OFF and wait one minute to deplete the backup power supply. Failure to follow this instruction may result in serious personal injury or death in the event of an accidental deployment.

- Disconnect: BTS (Belt Tension Sensor) C3238.

- Measure the resistance between BTS (Belt Tension Sensor) :
- C3238-1, circuit VR210 (BU/BN, harness side and ground.

- C3238-3, circuit LR142 (YE/BU), harness side and ground.






Are the resistances greater than 10,000 ohms?

Yes
GO to AP11.

No
REPAIR circuit VR210 (BU/BN or LR142 (YE/BU). GO to AP15.

AP11 CHECK OCSM (Occupant Classification System Module) OUTPUT

- Connect: OCSM (Occupant Classification System Module) C3159.

- Ignition ON.

- Measure the voltage between BTS (Belt Tension Sensor) C3238-3, circuit LR142 (YE/BU), harness side and C3238-2, circuit GD901 (BK), harness side.





Is the voltage approximately 5 volts?

Yes
GO to AP12.

No
INSTALL a new OCS (Occupant Classification System) system service kit. REFER to Occupant Classification Sensor . GO to AP15.

AP12 CHECK BTS (Belt Tension Sensor) VOLTAGE OUTPUT

- Ignition OFF.

- Depower the SRS (Supplemental Restraint System). Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.

- Disconnect: Passenger Seat Side Air Bag Module C339.

- Connect a fused jumper wire between BTS (Belt Tension Sensor) C3238 pin 3, circuit LR142 (YE/BU), harness side and pin 3, component side.

- Connect a fused jumper wire between BTS (Belt Tension Sensor) C3238 pin 2, circuit GD901 (BK), harness side and pin 2, component side.

- Repower the SRS (Supplemental Restraint System). Do not prove out the system at this time. Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.

- Ignition ON.

- Measure the voltage between BTS (Belt Tension Sensor) C3238 pin 1, component side and ground as the tension of the BTS (Belt Tension Sensor) varies by pulling upward at the safety belt webbing.





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?

Yes
GO to AP13.

No
INSTALL a new safety belt retractor assembly. GO to AP15.

AP13 CONFIRM THE OCSM (Occupant Classification System Module)

NOTE: Make sure all OCS (Occupant Classification System) system components, restraint system sensor electrical connectors and the RCM (Restraints Control Module) electrical connectors are connected before carrying out self-test. If not, DTCs will be recorded.

- Ignition OFF.

- Depower the SRS (Supplemental Restraint System). Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.

- Prior to reconnecting any previously disconnected SRS (Supplemental Restraint System) component:
- inspect connector(s) (including any in-line connectors) for pushed-out, loose or spread terminals and loose or frayed wire connections at terminals.

- inspect wire harness for any damage, pinched, cut or pierced wires.

- repair any concerns found.
Refer to Wiring Diagram Set 5, Connector Repair Procedures for schematic and connector information. Diagrams By Number

- Connect: OCSM (Occupant Classification System Module) C3159 (if disconnected previously).

- Connect: BTS (Belt Tension Sensor) C3238.

- Repower the SRS (Supplemental Restraint System). Do not prove out the SRS (Supplemental Restraint System) at this time. Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.

- Ignition ON.

- Enter the following diagnostic mode on the scan tool: Self Test- OCSM (Occupant Classification System Module).

- Enter the following diagnostic mode on the scan tool: DataLogger- OCSM (Occupant Classification System Module)- View and Record All 2909 Fault PIDs.
- Refer to PID list in Normal Operation to view 2909 fault PIDs.


Does the original on-demand 2909 fault PID indicate a fault?

Yes
INSTALL a new OCS (Occupant Classification System) system service kit. REFER to Occupant Classification Sensor . GO to AP15.

No
In the process of diagnosing the fault, the fault condition has become intermittent. Do not install any new SRS (Supplemental Restraint System) components at this time. SRS (Supplemental Restraint System) components should only be installed when directed to do so in the pinpoint test. GO to AP14.

AP14 CHECK FOR AN INTERMITTENT FAULT

- Ignition OFF.

- Disconnect BTS (Belt Tension Sensor) C3238:
- inspect connector(s) (including any in-line connectors) for loose or spread terminals and loose or frayed wire connections at terminals.
- inspect wire harness for any damage, pinched, cut or pierced wires.
- repair any concerns found.
Refer to Wiring Diagram Set 5, Connector Repair Procedures for schematic and connector information. Diagrams By Number

- Connect: All Previously Disconnected Component(s)/Connector(s).

- Ignition ON.

- Enter the following diagnostic mode on the scan tool: Self Test- OCSM (Occupant Classification System Module).

- Enter the following diagnostic mode on the scan tool: DataLogger- OCSM (Occupant Classification System Module)- View and Record All 2909 Fault PIDs.
- Refer to PID list in Normal Operation to view 2909 fault PIDs.


Do any on-demand 2909 fault PIDs indicate a fault?

Yes
This is a hard fault. This fault cannot be cleared until it is corrected and the DTC is no longer retrieved on-demand during self-test.

Using the on-demand fault PIDs recorded, GO to the appropriate pinpoint test step.

For fault PID 2909_31_OD, GO to AP2.

For fault PID 2909_28_OD, GO to AP8.

For 2909_30_OD, GO to AP9.

For fault PID 2909_29_OD, GO to AP10.

No
CHECK for causes of the intermittent fault. ATTEMPT to recreate the hard fault by flexing the wire harness and cycling the ignition frequently. ACTIVATE other systems in the same wire harness. Do not install any new SRS (Supplemental Restraint System) components at this time. SRS (Supplemental Restraint System) components should only be installed when directed to do so in the pinpoint test. REPAIR any intermittent wiring, terminal or connector concerns found. GO to AP15.

AP15 CHECK FOR ADDITIONAL SRS (Supplemental Restraint System) DTCs

- Ignition OFF.

WARNING: Turn the ignition OFF and wait one minute to deplete the backup power supply. Failure to follow this instruction may result in serious personal injury or death in the event of an accidental deployment.

- Reconnect all SRS (Supplemental Restraint System) components (if previously disconnected).

- If previously directed to depower the SRS (Supplemental Restraint System), repower the SRS (Supplemental Restraint System). Do not prove out the SRS (Supplemental Restraint System) at this time. Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.

- Ignition ON.

- Enter the following diagnostic mode on the scan tool: Self Test- Restraints.

NOTE: When selecting Restraints from the Self Test menu, DTCs will be retrieved from the RCM (Restraints Control Module) and OCSM (Occupant Classification System Module).


Are any RCM (Restraints Control Module) and/or OCSM (Occupant Classification System Module) DTCs retrieved?

Yes
Do not clear any DTCs until all DTCs have been resolved. GO to the DTC Charts for pinpoint test direction. Air Bag Systems/Seat Belt Systems

No
CLEAR all RCM (Restraints Control Module) and OCSM (Occupant Classification System Module) CMDTCs (Continuous Memory Diagnostic Trouble Codes). PROVE OUT the SRS (Supplemental Restraint System). Repair is complete. RETURN the vehicle to the customer.

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