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Home >> Mercury >> 2009 >> Grand Marquis V8-4.6L Flex Fuel >> Repair and Diagnosis >> Restraints and Safety Systems >> Air Bag Systems >> Testing and Inspection >> Pinpoint Tests >> Pinpoint Test G: DTC B1892

Pinpoint Test G: DTC B1892




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

Pinpoint Test G: DTC B1892

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 B1892:

- LFC 5-3 - Air Bag Tone Warning Indicator Circuit Open or Short to Ground

Normal Operation

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

If the RCM detects an open or short to ground on the circuit to the LCM, it will store DTC B1892 in memory, flash LFC 5-3 on the air bag warning indicator.

- DTC B1892 Air Bag Tone Warning Indicator Circuit Open or Short to Ground - If the RCM detects an open circuit or short to ground when the indicator is not active, it will set this DTC.

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



PINPOINT TEST G: DTC B1892

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.

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

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.

NOTE: 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

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G1 RETRIEVE SRS DTCs


- Enter the following diagnostic mode on the scan tool: Self Test - RCM.
- Was DTC B1892 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 on-demand during self test. GO to G2.

No
This is an intermittent fault when present as a CMDTC only. GO to G6.

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G2 CHECK THE AIR BAG TONE WARNING INDICATOR CIRCUIT 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: RCM C310a and C310b.
- Disconnect: LCM C2145a.
- Measure the resistance between RCM C310a-23, circuit 1083 (LB/PK), harness side and ground.




- Is the resistance greater than 10,000 ohms?

Yes
GO to G3.

No
REPAIR circuit 1083 (LB/PK). GO to G7.

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G3 CHECK THE AIR BAG TONE WARNING INDICATOR CIRCUIT FOR AN OPEN


- Measure the resistance between RCM C310a-23, circuit 1083 (LB/PK), harness side and LCM C2145a-4, circuit 1083 (LB/PK), harness side.




- Is the resistance less than 0.5 ohm?

Yes
GO to G4.

No
REPAIR circuit 1083 (LB/PK). GO to G7.

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G4 CHECK THE AIR BAG TONE WARNING INDICATOR


- Connect: LCM C2145a.
- Deactivate the system. Refer to Supplemental Restraint System (SRS) Deactivation and Reactivation Supplemental Restraint System (SRS) Deactivation and Reactivation.
- Ignition ON.
- Measure the voltage between RCM C310a-23, circuit 1083 (LB/PK), harness side and ground.




- Is voltage greater than 10 volts?

Yes
GO to G5.

No
INSTALL a new LCM. GO to G7.

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G5 CONFIRM THE RCM FAULT


NOTE: Make sure all restraint system diagnostic tools, sensor electrical connectors and the RCM electrical connectors are connected before carrying out the 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.
- Connect: LCM C2145a.
- 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.
- Enter the following diagnostic mode on the scan tool: Self Test - RCM.
- Was DTC B1892 retrieved on-demand during self-test?

Yes
INSTALL a new RCM. REFER to Restraints Control Module (RCM) Service and Repair. GO to G7.

No
CHECK for causes of intermittent short to ground or open 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. REPAIR any intermittent wiring, terminal or connector concerns found. GO to G7.

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G6 CHECK FOR AN INTERMITTENT FAULT


- Enter the following diagnostic mode on the scan tool: Self Test - RCM.
- Was DTC B1892 retrieved on-demand during self-test?

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

No
CHECK for causes of intermittent short to ground or open 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 G7.

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G7 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.
- If previously directed to deactivate the SRS, reactivate the SRS. Do not prove out the SRS at this time. Refer to Supplemental Restraint System (SRS) Deactivation and Reactivation Supplemental Restraint System (SRS) Deactivation and Reactivation.
- Are any DTCs retrieved on-demand during self-test?

Yes
Do not clear any DTCs until all DTCs have been resolved. GO to the Supplemental Restraint System (SRS) DTC Chart for pinpoint test direction. Diagnostic Trouble Code Tests and Associated Procedures

No
CLEAR all CMDTCs. PROVE OUT the SRS. REPAIR is complete. RETURN the vehicle to the customer.

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