Operation CHARM: Car repair manuals for everyone.
Home >> Lincoln >> 2009 >> Town Car V8-4.6L Flex Fuel >> Repair and Diagnosis >> Restraints and Safety Systems >> Air Bag Systems >> Testing and Inspection >> Pinpoint Tests >> Pinpoint Test H: DTC B1892

Pinpoint Test H: DTC B1892




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


Pinpoint Tests


Pinpoint Test H: 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 Failure

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 and 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 H: 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) 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 Supplemental Restraint System (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.

-------------------------------------------------
H1 CHECK FOR ON-DEMAND AND CONTINUOUS 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 during the on-demand self-test. GO to H2.

No
This is an intermittent fault when present as a continuous memory DTC only (DTC not retrieved on demand). The fault condition is not present at this time. GO to H6.

-------------------------------------------------
H2 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 H3.

No
REPAIR circuit 1083 (LB/PK). GO to H7.

-------------------------------------------------
H3 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 H4.

No
REPAIR circuit 1083 (LB/PK). GO to H7.

-------------------------------------------------
H4 CHECK THE AIR BAG TONE WARNING INDICATOR


- Connect: LCM C2145a.
- Deactivate the SRS. 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 H5.

No
INSTALL a new LCM. GO to H7.

-------------------------------------------------
H5 CONFIRM THE RCM FAULT


NOTE: Make sure all Restraint System Diagnostic Service Tools, sensor electrical connectors and the RCM electrical connectors are connected before carrying out the self-test. If not, erroneous DTCs will be recorded.

- Ignition OFF.
- Connect: RCM C310a and C310b.
- 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 H7.

No
In the process of diagnosing the fault, the fault condition has become intermittent. CHECK for causes of the intermittent fault in the areas previously worked in, particularly the pins and terminals of electrical connectors that were disconnected. 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 H7.

-------------------------------------------------
H6 CHECK FOR AN INTERMITTENT FAULT


- Ignition OFF.
- 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 during the on-demand self-test. GO to H2.

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 H7.

-------------------------------------------------
H7 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 notprove out the SRS at this time. Refer to Supplemental Restraint System (SRS) Deactivation and Reactivation Supplemental Restraint System (SRS) Deactivation and Reactivation.
- 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.

-------------------------------------------------
pro multis · About Operation CHARM