For circuit and connector information, refer to Wiring Diagrams Cell 46.
Normal Operation and Fault Symptoms
The Seat Belt Tension Sensor (BTS) works together with the OCS. The OCSM supplies a reference voltage to the BTS, which changes as it passes through the sensor depending on the amount of tension applied to the seat belt and the BTS.
The OCSM monitors the BTS reference voltage circuit for a short to battery voltage or a short to ground.
When a fault is detected, the OCSM stores DTC B00C2:11 or B00C2:12 in memory and sends a message to the RCM over HS-CAN indicating that an OCS fault is present. On receiving this message, the RCM sets DTC B00A0:09 and sends a message to the IPC to illuminate the airbag warning indicator.
DTC Fault Trigger Conditions
Trouble Code
Description
Fault Trigger Conditions
B00C2:11
Passenger Seat Occupant Classification Sensor "C": short to ground
Fault is indicated when the OCSM detects a short to ground in the BTS reference voltage circuit.
B00C2:12
Passenger Seat Occupant Classification Sensor "C": Short to Battery
Fault is indicated when the OCSM detects a short to voltage in the BTS reference voltage circuit.
Possible Causes
Wiring, Terminals or Connectors
Belt Tension Sensor (BTS) (part of the front passenger right seatbelt pretensioner)
OCSM
Visual Inspection and Preliminary Diagnosis
Inspect the front passenger seatbelt or Belt Tension Sensor (BTS) for damage.
Inspect the front passenger seat cushion airbag harness for damage.
Inspect the OCSM or seat belt tension sensor (BTS) connector for looseness or damage.
Inspect the OCSM for damage.
PINPOINT TEST A: B00C2:11 AND B00C2:12
NOTE: Most concerns are related to connector and/or wiring issues. Perform a thorough inspection and check before proceeding to the Pinpoint Test.
NOTE: Only disconnect or reconnect SRS components when instructed to do so in the Pinpoint Test step. Failure to follow this instruction may result in an incorrect SRS diagnosis.
NOTE: Always verify the correct SRS component is installed. Parts released for other vehicles may be incompatible even if they appear physically similar. Check the part number listed in the Ford parts catalog to confirm the correct component is installed. If an incorrect SRS component is installed, diagnostic trouble codes (DTCs) may be set.
NOTE: Before returning the vehicle to the customer, the SRS must be fully functional and operating correctly.
WARNING: Before starting any service procedure in this section, refer to the Safety Warnings in Section 100-00 General Information. Failure to follow this instruction may result in serious personal injury. REFER TO: Pyrotechnic Device Handling Precautions (100-00 General Information, Description and Operation).
The ignition is on.
Using the diagnostic scan tool, perform the OCSM self-test.
Was DTC B00C2:11 or B00C2:12 retrieved on demand during the Self-Test?
Yes
This fault cannot be cleared until it is repaired and the DTC is no longer retrieved on demand during the Self-Test. For DTC B00C2:11 GO to A2 For DTC B00C2:12 GO to A4
No
This is an intermittent fault when it is present only as a continuous memory Diagnostic Trouble Code (CMDTC). GO to A6
A2 CHECK THE SEAT BELT TENSION SENSOR (BTS)
Ignition OFF.
Disconnect: Front Passenger Seatbelt Belt Tension Sensor (BTS) C3238.
Using the diagnostic scan tool, perform the OCSM self-test.
DIAGNOSTIC TIP: When viewing Diagnostic Trouble Codes (DTCs) with the Belt Tension Sensor (BTS) disconnected, an open circuit is usually cleared. Because the Belt Tension Sensor (BTS) shares a connector with the front passenger seatbelt buckle switch, a circuit fault in the front passenger seatbelt buckle switch will also be present in the RCM.
Was DTC B00C2:11 retrieved on demand during the Self-Test?
Yes
GO to A3
No
INSTALL a new front passenger seatbelt pretensioner assembly. REFER TO: Retractor and Pretensioner Seatbelt (501-20A Seating Systems, Removal and Installation). GO to A7
A3 CHECK THE BELT TENSION SENSOR (BTS) VREF CIRCUIT FOR A SHORT TO GROUND
Ignition OFF.
Disconnect: OCSM C3159.
Action: Click to display the connectors
Positive lead
Measurement/Action
Negative lead
C3238-1
Ground
Is the resistance greater than 10000 Ohms?
Yes
GO to A5
No
REPAIR the circuit. For wiring diagrams and connector information, refer to Wiring Diagrams, Cell 5. GO to A7
A4 CHECK THE BELT TENSION SENSOR (BTS) VREF CIRCUIT FOR A SHORT TO VOLTAGE
Ignition OFF.
De-power the SRS. REFER to: Supplemental Restraint System (SRS) Disabling and Re-enabling (501-20B Supplemental Restraint System, General Procedures).
Disconnect: Passenger Side Airbag C337.
Disconnect: Front Passenger Seatbelt Belt Tension Sensor (BTS) C3238.
Disconnect: OCSM C3159.
Reset the SRS. Do not check the SRS at this time. REFER TO: Supplemental Restraint System (SRS) Disarming and Rearming (501-20B Supplemental Restraint System, General Procedures).
The ignition is on.
Action: Click to display the connectors
Positive lead
Measurement/Action
Negative lead
C3238-1
Ground
Is there voltage present?
Yes
REPAIR the circuit. For wiring diagrams and connector information, refer to Wiring Diagrams, Cell 5. GO to A7
No
GO to A5
A5 CONFIRM OCSM (OCCUPANT CLASSIFICATION SYSTEM MODULE) FAULT
Ignition OFF.
Before reconnecting any previously disconnected SRS component:
inspect the connector(s) (including any integral connectors) for pushed-out, loose or spread terminals, and loose or chafed wire connections at the terminals.
Inspect the wiring harness for damage, pinching, cuts or punctures in the wires.
repair any problems found. Refer to Wiring Diagrams Cell 5 for schematic and connector information.
Connect: Front Passenger Seatbelt Belt Tension Sensor (BTS) C3238 (if previously disconnected).
Connect: OCSM C3159 (if previously disconnected).
If the front passenger side airbag C337 was previously disconnected, enable the SRS. REFER TO: Supplemental Restraint System (SRS) Disabling and Enabling (501-20B Supplemental Restraint System, General Procedures).
Connect: Passenger Side Airbag C337.
If previously instructed to disable the SRS, re-enable the SRS. Do not check the SRS at this time. Refer to: Supplemental Restraint System (SRS) Disabling and Arming (501-20B Supplemental Restraint System, General Procedures).
The ignition is on.
Using the diagnostic scan tool, perform the OCSM self-test.
Was the original DTC retrieved on demand during the self-test?
Yes
CHECK OASIS for any applicable Technical Service Bulletins (TSBs). If a TSB exists for this condition, STOP this test and FOLLOW the TSB instructions. If the TSBs do not address this concern, INSTALL a new OCS sensor. REFER TO: Occupant Classification Sensor (OCS) (501-20B Supplemental Restraint System, Removal and Installation). GO to A7
No
During the diagnosis, the condition became intermittent. Do not install new SRS components at this time. Install SRS components only when directed to do so in the pinpoint test. GO to A6
A6 CHECK FOR INTERMITTENT FAULT
Ignition OFF.
Disconnect: Front Passenger Seatbelt Belt Tension Sensor (BTS) C3238.
Inspect the connector(s) (including any inline connectors) for loose or spread terminals and loose or worn wire-to-terminal connections.
Inspect the wiring harness for damage, pinching, cuts or punctures in the wires.
repair any problems found. Refer to Wiring Diagrams Cell 5 for schematic and connector information.
Connect: Front Passenger Seatbelt Belt Tension Sensor (BTS) C3238.
The ignition is on.
Using a diagnostic scan tool, perform the OCSM Self-Test to retrieve Diagnostic Trouble Codes (DTCs).
Was DTC B00C2:11 or B00C2:12 retrieved on demand during the Self-Test?
Yes
The fault condition is now present. This fault cannot be cleared until it is repaired, and the DTC is no longer retrieved on demand during the Self-Test. For DTC B00C2:11 GO to A2 For DTC B00C2:12 GO to A4
No
CHECK for the cause of an intermittent fault. TRY to recreate the fault by flexing the wiring harness and cycling the ignition frequently. ACTIVATE the other system in the same wiring harness. Do not install any new SRS components at this time. Install SRS components only when directed by the pinpoint test. REPAIR any intermittent concern found. GO to A7.
A7 CHECK THE SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DIAGNOSTIC TROUBLE CODES (DTCS)
Ignition OFF.
If the front passenger side airbag C337 was previously disconnected, enable the SRS. REFER TO: Supplemental Restraint System (SRS) Disabling and Enabling (501-20B Supplemental Restraint System, General Procedures).
Reconnect all SRS components (if previously disconnected).
If previously instructed to disable the SRS, re-enable the SRS. Do not check the SRS at this time. Refer to: Supplemental Restraint System (SRS) Disabling and Arming (501-20B Supplemental Restraint System, General Procedures).
The ignition is on.
NOTE: When Restraints is selected in the Self Test menu, DTCs are retrieved from the RCM and OCSM. Using the diagnostic scanner, perform the Restraints Self Test.
Were any Diagnostic Trouble Codes (DTCs) retrieved from the RCM and/or OCSM?
Yes
Do not clear any Diagnostic Trouble Codes (DTCs) until all DTCs have been resolved. DIAGNOSE and REPAIR the RCM and/or OCSM DTCs. REFER TO: Supplemental Restraint System (SRS) (501-20 Supplemental Restraint System).
No
CLEAR all RCM and OCSM diagnostic trouble codes (DTCs). VERIFY SRS repair. Repair is complete. RETURN the vehicle to the customer.
?
Test yourself
A quick Ford Fiesta quiz: every answer comes with an explanation and a link to the manual page.
WARNING: Before starting any service procedure in this section, refer to the Safety Warnings in Section 100-00 General Information. Failure to follow this instruction may result in serious personal injury. 
