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Pinpoint Test G: DTC B1891




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

Pinpoint Test G: DTC B1891

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

Lamp Fault Codes (LFCs)

The following Lamp Fault Code (LFC) indicates the specific fault associated with DTC B1891:

- LFC 10-15 - Air Bag Tone Warning Indicator Circuit Short to Battery

Normal Operation

The Restraints Control Module (RCM) monitors its connection to the Lighting Control Module (LCM) at C310a pin 23. This connection is used to signal a chime if the air bag warning indicator is inoperative and another Supplemental Restraint System (SRS) fault exists.

If the RCM detects a short to battery on the connection to the LCM, it will store DTC B1891 in memory and flash LFC 10-15 on the air bag warning indicator.

- DTC B1891 (Air Bag Tone Warning Indicator Circuit Short to Battery) - If the RCM detects a short to battery on the air bag tone warning indicator circuit, it will set this DTC.

This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- LCM
- RCM


PINPOINT TEST G: DTC B1891

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 disassemble or tamper with safety belt buckle/retractor pretensioners or adaptive load limiting retractors or probe the electrical connectors. 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 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: The SRS must be fully operational and free of faults before releasing the vehicle to the customer.

NOTE: 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.

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G1 CHECK FOR ON-DEMAND AND CONTINUOUS DTCs


- Enter the following diagnostic mode on the scan tool: Self-Test - RCM.
- Was DTC B1891 retrieved on-demand during self-test?

Yes
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. GO to G2.

No
This is an intermittent fault when present as a Continuous Memory Diagnostic Trouble Code (CMDTC) only (DTC not retrieved on demand). The fault condition is not present at this time. GO to G4.

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G2 CHECK THE AIR BAG TONE WARNING INDICATOR CIRCUIT 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: RCM C310a and C310b.
- Disconnect: LCM C2145a.
- 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 LCM C2145a-4, circuit 1083 (LB/PK), harness side and ground.




- Is any voltage present?

Yes
REPAIR circuit 1083 (LB/PK). GO to G5.

No
GO to G3.

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G3 CHECK THE AIR BAG TONE WARNING INDICATOR CIRCUIT


- 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.
- 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.
- NOTE: DTC B1892 should be retrieved when carrying out the self-test due to an open circuit 1083 (LB/PK), DTC B1891 should not be retrieved at this time.
- Was DTC B1891 retrieved on-demand during self-test?

Yes
INSTALL a new RCM. REFER to Restraints Control Module (RCM) Service and Repair. GO to G5.

No
INSTALL a new LCM. REFER to Multifunction Electronic Modules Lighting Control Module (LCM). GO to G5.

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G4 CHECK FOR AN INTERMITTENT FAULT


- Ignition OFF.
- Enter the following diagnostic mode on the scan tool: Self-Test - RCM.
- Was DTC B1891 retrieved on-demand during self-test?

Yes
The fault condition is now present. This fault cannot be cleared until it is corrected and DTC is no longer retrieved during the on-demand self-test. GO to G2.

No
CHECK for causes of an intermittent short to voltage on circuit 1083 (LB/PK). 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. 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 G5.

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G5 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 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.
- Are any RCM DTCs retrieved on-demand during self-test?

Yes
Do not clear any DTCs until all DTCs have been resolved. GO to the DTC Charts for pinpoint test direction. [1][2]Diagnostic Trouble Code Descriptions

No
CLEAR all RCM continuous memory DTCs. PROVE OUT the SRS. Repair is complete. RETURN the vehicle to the customer.

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