Pinpoint Test N: LFC 51/DTC B2691
Air Bag and Safety Belt Pretensioner Supplemental Restraint System (SRS)
Pinpoint Tests
Pinpoint Test N: LFC 51/DTC B2691
Refer to Wiring Diagram Set 46, Supplemental Restraint System for schematic and connector information. Diagrams By Number
Normal Operation
The Restraints Control Module (RCM) checks the driver safety belt buckle switch circuits for faults. If the RCM detects an open circuit or short to voltage, it will set and store DTC B2691 in memory and send a message to the Instrument Cluster (IC) module to flash Lamp Fault Code (LFC) 51 (or higher priority code if one exists) on the air bag warning indicator.
- DTC B2691 (Seat Belt Buckle Switch Circuit Fault, Front Driver's Side) - If the RCM detects an open or short to battery on the driver safety belt buckle switch circuit for greater than 2.5 seconds, it will set this DTC.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Driver safety belt buckle switch
- RCM
PINPOINT TEST N: LFC 51/DTC B2691
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.
NOTE: The SRS must be fully operational and free of faults before releasing the vehicle to the customer.
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N1 RETRIEVE RCM DTCs
- Enter the following diagnostic mode on the scan tool: Self Test - RCM.
- Was DTC B2691 retrieved on-demand during self-test?
Yes
This fault cannot be cleared until it is corrected and the DTC is no longer retrieved on-demand during self-test. GO to N2.
No
This is an intermittent fault when present as a Continuous Memory Diagnostic Trouble Code (CMDTC) only. GO to N7.
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N2 CHECK DRIVER SAFETY BELT BUCKLE SWITCH CIRCUIT FOR AN OPEN
- Ignition OFF.
- Depower the SRS. Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.
- Disconnect: RCM C310A and C310B.
- Disconnect: Driver Safety Belt Buckle Switch C3065.
- Measure the resistance between RCM C310B-25, circuit CR201 (GN/BU), harness side and driver safety belt buckle switch C3065-1, circuit CR201 (GN/BU), harness side.
- Is the resistance less than 0.5 ohm?
Yes
GO to N3.
No
REPAIR circuit CR201 (GN/BU). GO to N8.
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N3 CHECK FOR AN OPEN GROUND CIRCUIT
- Measure the resistance between driver safety belt buckle switch C3065-2, circuit GD174 (BK/WH), harness side and ground.
- Is the resistance less than 0.5 ohm?
Yes
GO to N4.
No
REPAIR circuit GD174 (BK/WH). GO to N8.
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N4 CHECK DRIVER SAFETY BELT BUCKLE SWITCH CIRCUIT FOR A SHORT TO VOLTAGE
- 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 driver safety belt buckle switch C3065-1, circuit CR201 (GN/BU), harness side and ground.
- Is any voltage present?
Yes
REPAIR circuit CR201 (GN/BU). GO to N8.
No
GO to N5.
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N5 CHECK THE DRIVER SAFETY BELT BUCKLE SWITCH
- Ignition OFF.
- Depower the SRS. Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.
- Connect: RCM C310A and C310B.
- Install a known good driver safety belt buckle assembly. Refer to Restraint Systems.
- Connect: Driver Safety Belt Buckle Switch C3065.
- 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.
- Enter the following diagnostic mode on the scan tool: Self Test - RCM.
- Was DTC B2691 retrieved on-demand during self-test?
Yes
GO to N6.
No
Fault corrected. GO to N8.
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N6 CONFIRM THE RCM FAULT
NOTE: Make sure all restraint system components and the RCM electrical connectors are connected before carrying out self-test. If not, 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.
- Reinstall the original driver safety belt buckle assembly. REFER to Restraint Systems.
- 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.
- Enter the following diagnostic mode on the scan tool: Self Test - RCM.
- Was DTC B2691 retrieved on-demand during self-test?
Yes
INSTALL a new RCM. REFER to Restraints Control Module (RCM) Service and Repair. GO to N8.
No
In the process of diagnosing the fault, the fault condition has become intermittent. 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 N8.
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N7 CHECK FOR AN INTERMITTENT FAULT
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: Self Test - RCM.
- Was DTC B2691 retrieved on-demand during self-test?
Yes
This fault cannot be cleared until it is corrected and the DTC is no longer retrieved on-demand during self-test. GO to N2.
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. 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 N8.
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N8 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 indicating a fault?
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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