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Home >> Lincoln >> 2009 >> MKS FWD V6-3.7L >> Repair and Diagnosis >> Restraints and Safety Systems >> Air Bag Systems >> Testing and Inspection >> Pinpoint Tests >> Pinpoint Test D: LFC 38/39 DTC B1085 >> D1-D13

D1-D13




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

Pinpoint Tests

Pinpoint Test D: LFC 38/39 DTC B1085

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

Normal Operation

The Restraints Control Module (RCM) continuously monitors the safety belt retractor adaptive load limiting circuits for the following faults:

- Resistance out of range
- Unexpected voltage
- Short to ground

If a fault is detected, the RCM will set and store DTC B1085 in memory and send a message to the Instrument Cluster (IC) module to flash a Lamp Fault Code (LFC) 38 or 39 on the air bag warning indicator. After the LFC(s) are displayed, the air bag warning indicator will remain illuminated for the rest of the ignition cycle.

The RCM monitors the safety belt adaptive load limiting retractor circuits for resistance and expects a normal resistance between 1.50 and 3.04 ohms.

If resistance is between 1.04 and 1.50 ohms or between 3.04 and 3.72 ohms, there exists a strong potential for a fault to occur (a DTC may or may not set). The RCM will also set a DTC if loop resistance is less than 1.04 ohms or greater than 3.72 ohms.





a Fault PIDs that end in OD indicate an on-demand status and are associated with on-demand DTC B1085. Fault PIDs that end in CM indicate continuous memory status and are associated with continuous DTC B1085.

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



PINPOINT TEST D: LFC 38/39 DTC B1085

WARNING: Do not handle, move or change the original horizontal mounting position of the restraints control module (RCM) while the RCM is connected and the ignition switch is ON. Failure to follow this instruction may result in the accidental deployment of the Safety Canopy(R) and cause 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: The Supplemental Restraint System (SRS) must be fully operational and free of faults before releasing the vehicle to the customer.

NOTE: SRScomponents 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 theSRS.

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D1 RETRIEVE RCM DTCs


- 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 1085 Fault PIDs.
- Refer to PID list in Normal Operation to view 1085 fault PIDs.
- Do any on-demand 1085 fault PIDs indicate a fault?

Yes
This fault cannot be cleared until it is corrected and the DTC is no longer retrieved on-demand during self test.

For 1085_28_OD, GO to D2.

For 1085_29_OD, GO to D2.

For 1085_31_OD, GO to D8.

For 1085_30_OD, GO to D10.

For 1085_24_OD, GO to D11.

For 1085_25_OD, GO to D11.

For 1085_27_OD, GO to D17.

For 1085_26_OD, GO to D19.

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

For 1085_28_CM, 1085_29_CM, 1085_24_CM or 1085_25_CM, GO to D22.

For 1085_31_CM or 1085_27_CM, GO to D24.

For 1085_30_CM or 1085_26_CM, GO to D25.

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D2 CHECK THE DRIVER SAFETY BELT LOAD LIMITING RETRACTOR RESISTANCE (D_LOAD) PID


- Enter the following diagnostic mode on the scan tool: DataLogger - RCM .
- Enter the following diagnostic mode on the scan tool: D_LOAD PID .
- Does the PID value read between 1.50 and 3.04 ohms?

Yes
GO to D21.

No
GO to D3.

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D3 CHECK THE DRIVER SAFETY BELT LOAD LIMITING RETRACTOR RESISTANCE (D_LOAD) PID WHILE CARRYING OUT A HARNESS TEST


- While monitoring the D_LOAD PID carry out a harness test of the driver safety belt load limiting retractor circuits and accessible connectors (including any in-line connectors), by wiggling connectors and flexing the wire harness.
- Does the PID value read between 1.50 and 3.04 ohms while carrying out a harness test?

Yes
DEPOWER the SRS and REPAIR the connector, terminals or wire harness as needed.

Refer to Wiring Diagram Set 5, Connector Repair Procedures for schematic and connector information. Diagrams By Number
GO to D26.

No
If the D_LOAD PID is less than 1.50 ohms, GO to D4.

If the D_LOAD PID is greater than 3.04 ohms, GO to D6.

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D4 CHECK THE DRIVER SAFETY BELT LOAD LIMITING RETRACTOR FAULT PID FOR A FAULT STATUS CHANGE (LOW RESISTANCE INDICATED)


NOTE: This pinpoint test step will attempt to change the fault reported by the RCM by inducing a different fault condition. If the fault reported changes, this indicates the RCM is functioning correctly and is not the source of the fault.

- Ignition OFF.
- Depower the SRS. Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.
- Disconnect: Driver Safety Belt Load Limiting Retractor C354.
- 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 the Following Fault PIDs.
- 1085_28_OD
- 1085_29_OD
- DIAGNOSTIC TIP: When viewing DTC B1085 on-demand fault PIDs with the driver safety belt load limiting retractor disconnected, an open circuit fault would normally be retrieved.
- Did the on-demand fault PIDs change from indicating a low resistance to an open circuit fault?

Yes
GO to D20.

No
GO to D5.

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D5 CHECK FOR A SHORT BETWEEN DRIVER SAFETY BELT LOAD LIMITING RETRACTOR CIRCUITS


- 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.
- Measure resistance between driver safety belt load limiting retractor C354-1, circuit CR146 (GY/VT), harness side and C354-2, circuit RR146 (BU/BN), harness side.




- Is the resistance greater than 10,000 ohms?

Yes
GO to D21.

No
REPAIR circuits CR146 (GY/VT) and RR146 (BU/BN). GO to D26.

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D6 CHECK THE DRIVER SAFETY BELT LOAD LIMITING RETRACTOR FAULT PID FOR A FAULT STATUS CHANGE (OPEN INDICATED)


NOTE: This pinpoint test step will attempt to change the fault reported by the RCM by inducing a different fault condition. If the fault reported changes, this indicates the RCM is functioning correctly and is not the source of the fault.

- Ignition OFF.
- Depower the SRS. Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.
- Disconnect: Driver Safety Belt Load Limiting Retractor C354.
- Connect a fused jumper wire between driver safety belt load limiting retractor C354-1, circuit CR146 (GY/VT), harness side and C354-2, circuit RR146 (BU/BN), harness side.
- 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 the Following Fault PIDs .
- 1085_28_OD
- 1085_29_OD
- DIAGNOSTIC TIP: When viewing DTC B1085 on-demand fault PIDs with the driver safety belt load limiting retractor circuits shorted together, a low resistance fault would normally be retrieved.
- Did the on-demand fault PIDs change from indicating an open circuit to a low resistance fault?

Yes
GO to D20.

No
GO to D7.

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D7 CHECK THE DRIVER SAFETY BELT LOAD LIMITING RETRACTOR CIRCUITS FOR AN OPEN


- Ignition OFF.
- Depower the SRS. Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.
- Remove the fused jumper wire from the driver safety belt load limiting retractor C354.
- Disconnect: RCM C310a and C310b.
- Measure resistance between RCM, harness side and driver safety belt load limiting retractor C354, harness side using the following chart.









- Are the resistances less than 0.5 ohm?

Yes
GO to D21.

No
REPAIR circuit CR146 (GY/VT) or RR146 (BU/BN). GO to D26.

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D8 CHECK THE DRIVER SAFETY BELT LOAD LIMITING RETRACTOR FAULT PID FOR A FAULT STATUS CHANGE (SHORT TO GROUND INDICATED)


NOTE: This pinpoint test step will attempt to change the fault reported by the RCM by inducing a different fault condition. If the fault reported changes, this indicates the RCM is functioning correctly and is not the source of the fault.

- Ignition OFF.
- Depower the SRS. Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.
- Disconnect: Driver Safety Belt Load Limiting Retractor C354.
- 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 the Following Fault PIDs .
- 1085_29_OD
- 1085_31_OD
- DIAGNOSTIC TIP: When viewing DTC B1085 on-demand fault PIDs with the driver safety belt load limiting retractor disconnected, an open circuit fault would normally be retrieved.
- Did the on-demand fault PIDs change from indicating a short to ground to an open circuit fault?

Yes
GO to D20.

No
GO to D9.

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D9 CHECK THE DRIVER LOAD LIMITING RETRACTOR CIRCUITS 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.
- Measure the resistance between driver load limiting retractor:
- C354-1, circuit CR146 (GY/VT), harness side and ground.
- C354-2, circuit RR146 (BU/BN) and ground.




- Are the resistances greater than 10,000 ohms?

Yes
GO to D21.

No
REPAIR circuit CR146 (GY/VT) or RR146 (BU/BN). GO to D26.

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D10 CHECK THE DRIVER LOAD LIMITING RETRACTOR CIRCUITS 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: Driver Load Limiting Retractor C354.
- Disconnect: 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.
- Measure the voltage between driver safety belt retractor retractor:
- C354-1, circuit CR146 (GY/VT), harness side and ground.
- C354-2, circuit RR146 (BU/BN), harness side and ground.




- Is voltage present on either circuit?

Yes
REPAIR the affected circuit. GO to D26.

No
GO to D21.

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D11 CHECK THE PASSENGER SAFETY BELT LOAD LIMITING RETRACTOR RESISTANCE (P_LOAD) PID


- Enter the following diagnostic mode on the scan tool: DataLogger - RCM .
- Enter the following diagnostic mode on the scan tool: P_LOAD Resistance PID .
- Does PID value read between 1.50 and 3.04 ohms?

Yes
GO to D21.

No
GO to D12.

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D12 CHECK THE PASSENGER SAFETY BELT LOAD LIMITING RETRACTOR RESISTANCE (P_LOAD) PID WHILE CARRYING OUT A HARNESS TEST


- While monitoring the P_LOAD PID carry out a harness test of the passenger safety belt load limiting retractor circuits and accessible connectors (including any in-line connectors), by wiggling connectors and flexing the wire harness.
- Does the PID value read between 1.50 and 3.04 ohms while carrying out the harness test?

Yes
DEPOWER the SRS and REPAIR the connector, terminals or wire harness as needed.

Refer to Wiring Diagram Set 5, Connector Repair Procedures for schematic and connector information. Diagrams By Number
GO to D26.

No
If the P_LOAD PID is less than 1.50 ohms, GO to D13.

If the P_LOAD PID is greater than 3.04 ohms, GO to D15.

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D13 CHECK THE PASSENGER SAFETY BELT LOAD LIMITING RETRACTOR FAULT PID FOR A FAULT STATUS CHANGE (LOW RESISTANCE INDICATED)


NOTE: This pinpoint test step will attempt to change the fault reported by the RCM by inducing a different fault condition. If the fault reported changes, this indicates the RCM is functioning correctly and is not the source of the fault.

- Ignition OFF.
- Depower the SRS. Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.
- Disconnect: Passenger Safety Belt Retractor C389.
- 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 the Following Fault PIDs.
- 1085_24_OD
- 1085_25_OD
- DIAGNOSTIC TIP: When viewing DTC B1085 on-demand fault PIDs with the passenger safety belt retractor disconnected, an open circuit fault would normally be retrieved.
- Did the on-demand fault PIDs change from indicating a low resistance to an open circuit fault?

Yes
GO to D20.

No
GO to D14.

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