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Home >> Mercury >> 2009 >> Milan AWD L4-2.3L >> Repair and Diagnosis >> Restraints and Safety Systems >> Air Bag Systems >> Testing and Inspection >> Pinpoint Tests >> Pinpoint Tests - Restraints Control Module (RCM) >> Pinpoint Test P: DTC B2792

Pinpoint Test P: DTC B2792




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

Pinpoint Tests - Restraints Control Module (RCM)

Pinpoint Test P: DTC B2792

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

Normal Operation

The Restraints Control Module (RCM) monitors all the deployable devices for a cross link between the circuits of another deployable device. If the RCM detects a short between the circuits of the deployable devices, it will store DTC B2792 and send a message to the Instrument Cluster (IC) module to illuminate the air bag indicator.





a Fault PIDs that end in OD indicate an on-demand status and are associated with on-demand DTC B2792. Fault PIDs that end in CM indicate continuous memory status and are associated with continuous DTC B2792.

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



PINPOINT TEST P: DTC B2792

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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P1 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 2792 Fault PIDs .
- Refer to PID list in Normal Operation to view 2792 fault PIDs.
- Do any on-demand DTC B2792 fault PIDs indicate a fault?

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 P2.

No
This is an intermittent fault when present as a Continuous Memory Diagnostic Trouble Code (CMDTC). The fault condition is not present at this time. GO to P4.

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P2 CHECK DEPLOYABLE CIRCUITS FOR A CROSS LINK FAULT


- 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 ALL of the affected deployable devices.
- Using the fault PIDs recorded and the following table, measure the resistance between the circuits of the affected deployable devices.





- Are the resistances greater than 10,000 ohms between the affected circuits?

Yes
GO to P3.

No
REPAIR the affected circuits. GO to P5.

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P3 CONFIRM RCM FAULT


NOTE: Make sure all restraint system components, sensor electrical connectors and the RCM electrical connectors are connected before carrying out the on-demand self test. If not, DTCs will be recorded.

- Connect: RCM C310a and C310b.
- Connect: All Previously Disconnected SRS Components.
- 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 2792 Fault PIDs.
- Refer to PID list in Normal Operation to view 2792 fault PIDs.
- Does the original on-demand DTC B2792 fault PID indicate a fault?

Yes
INSTALL a new RCM. REFER to Restraints Control Module (RCM) Service and Repair. GO to P5.

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 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 P5.

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P4 CHECK FOR AN INTERMITTENT FAULT


- Depower the SRS. Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.
- If a cross link fault for driver air bag loop 1 or loop 2 is present continuous, remove the driver air bag module. Refer to Driver Air Bag Module Driver Air Bag Module.
- If a cross link fault for passenger air bag module loop 1 or loop 2 is present continuous, remove the passenger air bag module. Refer to Passenger Air Bag Module Passenger Air Bag Module.
- If a cross link fault for driver seat side air bag is present continuous, disconnect the driver seat side air bag module C327.
- If a cross link fault for passenger seat side air bag is present continuous, disconnect the passenger seat side air bag module C313.
- If a cross link fault for driver side air curtain module is present continuous, disconnect the driver side air curtain module C3055.
- If a cross link fault for passenger side air curtain module is present continuous, disconnect the passenger side air curtain module C3056.
- If a cross link fault for driver safety belt retractor pretensioner is present continuous, disconnect the driver safety belt retractor pretensioner C323.
- If a cross link fault for passenger safety belt retractor pretensioner is present continuous, disconnect the passenger safety belt retractor pretensioner C3202.
- 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 .
- Enter the following diagnostic mode on the scan tool: DataLogger - RCM - View and Record All 2792 Fault PIDs.
- Refer to PID list in Normal Operation to view 2792 fault PIDs.
- Do any on-demand DTC B2792 fault PIDs indicate a fault?

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 P2.

No
The fault is not present and cannot be recreated at this time.

CHECK for causes of the intermittent fault. ATTEMPT to recreate the hard fault by flexing the wire harness, cycling the ignition frequently and rotating the steering wheel (driver air bag module fault). 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 P5.

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P5 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 - Restraints.
- NOTE: When selecting Restraints from the Self Test menu, DTCs will be retrieved from the RCM and OCSM.
- Are any RCM and/or Occupant Classification System Module (OCSM) DTCs retrieved indicating a fault?

Yes
Do not clear any DTCs until all DTCs have been resolved. GO to the DTC Charts for pinpoint test direction. Diagnostic Trouble Code Tests and Associated Procedures

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

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