Pinpoint Test T: LFC 16/DTC B2909
Air Bag and Safety Belt Pretensioner Supplemental Restraint System (SRS)
Pinpoint Tests
Pinpoint Test T: LFC 16/DTC B2909
Refer to Wiring Diagram Set 46, Supplemental Restraint System for schematic and connector information. Diagrams By Number
NOTE: Lamp Fault Code (LFC) 16 is shared between DTC B2290 and DTC B2909.
Normal Operation
The Belt Tension Sensor (BTS) is part of the Occupant Classification Sensor (OCS) system. The OCS system interprets a variable voltage signal provided by the BTS to identify the possible presence of a child safety seat in the front passenger seat. The voltage output of the BTS is proportional to the amount of tension applied to the sensor by the belt. No tension-low voltage is approximately 0.95 volt and high tension-high voltage is approximately 3.8 volts.
The OCS system continuously monitors the BTS circuits. If the Occupant Classification System Module (OCSM) detects one of the following faults on any of the BTS circuits, it will report the failure to the Restraints Control Module (RCM). The RCM will store DTC B2909 in memory and flash either LFC 16 on the air bag warning indicator.
The OCS system components (seat cushion foam pad, bladder with pressure sensor and OCSM) are calibrated to each other and are serviced as an assembly. The OCS system components are not to be installed separately with the exception of the BTS. If a new OCS system component or seat cushion foam pad are needed, a new OCS system service kit must be installed as an assembly.
a Fault PIDs that end in OD indicate an on-demand status and are associated with on-demand DTC B2909. Fault PIDs that end in CM indicate continuous memory status and are associated with continuous DTC B2909.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- BTS
- OCSM
PINPOINT TEST T: LFC 16/DTC B2909
WARNING: Remove restraint system diagnostic tools from the vehicle prior to road testing. If tools are not removed, the supplemental restraint system (SRS) device may not deploy in a crash. Failure to follow this instruction may result in serious personal injury or death in a crash and possibly violate vehicle safety standards.
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 probe the electrical connectors on safety belt buckle/retractor pretensioners or adaptive load limiting retractors. Failure to follow this instruction may result in the accidental deployment of the safety belt pretensioners or adaptive load limiting retractors, which increases the risk of serious personal injury or death.
NOTICE: Use the correct probe adapter(s) from the Flex Probe Kit when making 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.
NOTE: The SRS must be fully operational and free of faults before releasing the vehicle to the customer.
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T1 RETRIEVE RCM DTCs
- Enter the following diagnostic mode on the scan tool: Self Test - RCM.
- Enter the following diagnostic mode on the scan tool: DataLogger - RCM - View and Record All 2909 Fault PIDs .
- Refer to PID list in Normal Operation to view B2909 fault PIDs.
- Do any on-demand DTC B2909 fault PIDs indicate a fault?
Yes
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 2909_31_OD (Front Passenger Side Belt Tension Sensor Circuit Fault), GO to T2.
For 2909_29_OD (Front Passenger Side Belt Tension Sensor Short to Ground), GO to T4.
No
This is an intermittent fault when present as a CMDTC only. The fault condition is not present at this time. GO to T9.
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T2 CHECK BTS CIRCUITS FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Depower the SRS. Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.
- Disconnect: Passenger Seat Side Air Bag C337.
- Connect: Restraint System Diagnostic Tool 418-133 to Passenger Seat Side Air Bag C337.
- Disconnect: BTS C3238.
- Disconnect: OCSM C3043.
- Repower the SRS. Do not prove out the SRS 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:
- C3043-11, circuit 2088 (TN/RD), harness side and ground
- C3043-13, circuit 2090 (DB/OG), harness side and ground
- C3043-12, circuit 2089 (OG/BK), harness side and ground.
- Is voltage present on any circuit?
Yes
REPAIR circuit 2088 (TN/RD), 2089 (OG/BK) or 2090 (DB/OG). GO to T10.
No
GO to T3.
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T3 CHECK BTS CIRCUITS FOR AN OPEN
- Ignition OFF.
- Depower the SRS. Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.
- Measure the resistance between OCSM C3043, harness side and BTS C3238, harness side using the following chart.
- Are the resistances less than 0.5 ohm?
Yes
GO to T5.
No
REPAIR circuit 2088 (TN/RD), 2089 (OG/BK) or 2090 (DB/OG).
GO to T10.
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T4 CHECK BTS CIRCUITS FOR A SHORT TO GROUND
- Ignition OFF.
- Depower the SRS. Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.
- Disconnect: Passenger Seat Side Air Bag C337.
- Connect: Restraint System Diagnostic Tool 418-133 to Passenger Seat Side Air Bag C337.
- Disconnect: OCSM C3043.
- Measure the resistance between OCSM:
- C3043-11, circuit 2088 (TN/RD), harness side and ground.
- C3043-12, circuit 2089 (OG/BK), harness side and ground.
- C3043-13, circuit 2090 (DB/OG), harness side and ground.
- Are the resistances greater than 10,000 ohms?
Yes
GO to T5.
No
REPAIR circuit 2088 (TN/RD), 2089 (OG/BK) or 2090 (DB/OG). GO to T10.
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T5 CHECK FOR A SHORT BETWEEN BTS CIRCUITS
- Measure the resistance between the OCSM C3043, harness side using the following chart:
- Are the resistances greater than 10,000 ohms?
Yes
GO to T6.
No
REPAIR circuit 2088 (TN/RD), 2089 (OG/BK) or 2090 (DB/OG). GO to T10.
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T6 CHECK THE OCSM OUTPUT
- Connect: OCSM C3043.
- Repower the SRS. Do not prove out the SRS 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 C3238-1, circuit 2088 (TN/RD), harness side and C3238-2, circuit 2090 (DB/OG), harness side.
- Is voltage approximately 5 volts?
Yes
GO to T7.
No
INSTALL a new OCS system service kit. REFER to Occupant Classification Sensor Service and Repair. GO to T10.
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T7 CHECK BTS VOLTAGE OUTPUT
- Ignition OFF.
- Depower the SRS. Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.
- Connect a fused jumper lead between BTS C3238-1, circuit 2088 (TN/RD), harness side and pin 1, circuit 2088 (TN/RD), component side.
- Connect a fused jumper lead between BTS C3238-2, circuit 2090 (DB/OG), harness side and pin 2, circuit 2090 (DB/OG), component side.
- Repower the SRS. Do not prove out the SRS 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 C3238-3, circuit 2089 (OG/BK), component side and ground as you vary the tension of the BTS by pulling on the safety belt webbing near the anchor of the safety belt.
- 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 T8.
No
INSTALL a new BTS (part of safety belt and retractor assembly). GO to T10.
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T8 CONFIRM THE OCS SYSTEM 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.
- Ignition OFF.
- Depower the SRS. Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.
- Connect: BTS C3238.
- Repower the SRS. Do not prove out the SRS at this time. Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.
- Enter the following diagnostic mode on the scan tool: Self Test - RCM.
- Enter the following diagnostic mode on the scan tool: DataLogger - RCM - View and Record All 2909 Fault PIDs .
- Refer to PID list in Normal Operation to view B2909 fault PIDs.
- Do any on-demand DTC B2909 fault PIDs indicate a fault?
Yes
INSTALL a new OCS system service kit. REFER to Occupant Classification Sensor Service and Repair. GO to T10.
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 components at this time. SRS 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 T10.
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T9 CHECK FOR AN INTERMITTENT FAULT
- Enter the following diagnostic mode on the scan tool: Self Test - RCM.
- Enter the following diagnostic mode on the scan tool: DataLogger - RCM - View and Record All 2909 Fault PIDs .
- Refer to PID list in Normal Operation to view B2909 fault PIDs.
- Do any on-demand DTC B2909 fault PIDs indicate a 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.
Using the fault PIDs recorded, GO to the appropriate pinpoint test step.
For 2909_31_OD (Front Passenger Side Belt Tension Sensor Circuit Fault), GO to T2.
For 2909_29_OD (Front Passenger Side Belt Tension Sensor Short to Ground), GO to T4.
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 components at this time. SRS 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 T10.
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T10 CHECK FOR ADDITIONAL SRS 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 components (if previously disconnected).
- If previously directed to depower the SRS, repower the SRS. Do notprove out the SRS 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 - RCM.
- Are any RCM DTCs retrieved on-demand during the self test?
Yes
Do not clear any DTCs until all DTCs have been resolved. GO to the DTC Chart for pinpoint test direction. Diagnostic Trouble Code Tests and Associated Procedures
No
CLEAR all RCM CMDTCs. PROVE OUT the SRS. Repair is complete. RETURN the vehicle to the customer.
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