Operation CHARM: Car repair manuals for everyone.
Home >> Mercury >> 2010 >> Mountaineer 4WD V8-4.6L >> Repair and Diagnosis >> Restraints and Safety Systems >> Air Bag Systems >> Testing and Inspection >> Pinpoint Tests >> Pinpoint Test T: DTC B2985

Pinpoint Test T: DTC B2985




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

Pinpoint Tests

Pinpoint Test T: DTC B2985

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

Normal Operation

As part of the Supplemental Restraint System (SRS), this vehicle is equipped a deployable steering column. The Restraints Control Module (RCM) will deploy (collapse) the steering column during a frontal collision when seat position information and other parameters reach predetermined limits. Refer to Air Bag and Safety Belt Pretensioner Supplemental Restraint System (SRS) Description and Operation.

The RCM continuously monitors the deployable steering column circuits (loop) for an acceptable resistance range, unacceptable voltage and shorts to ground. The RCM will set on-demand and store a DTC (B2984, B2985, B2986 or B2987) in memory if any of these conditions are detected. If the RCM detects a fault, it will send a message to the Instrument Cluster (IC) module to illuminate the air bag warning indicator.

As the RCM continuously monitors deployable steering column circuits for resistance, it expects a normal resistance between 1.31 to 4.29 ohms.

If a loop resistance is between 0.9 and 1.31 or between 4.29 and 5 ohms, there exists a strong potential for an intermittent fault, a DTC may or may not set. The RCM will also set an on-demand DTC B2984 or B2987 respectfully if the loop resistance is less than 0.9 ohm or greater than 5 ohms.

- DTC B2985 (Deployable Steering Column Circuit Short to Battery) - If the RCM detects a short to voltage on the deployable steering column circuits, it will set this DTC.

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



PINPOINT TEST T: DTC B2985

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 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 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: 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.

-------------------------------------------------
T1 RETRIEVE RCM DTCs


- Enter the following diagnostic mode on the scan tool: Self Test - RCM.
- Was DTC B2985 retrieved on-demand during self-test?

Yes
The fault condition is still present. This fault cannot be cleared until it is corrected and DTC is no longer retrieved during the on-demand self test. GO to T2.

No
This is an intermittent fault when present as a CMDTC only. The fault condition is not present at this time. GO to T4.

-------------------------------------------------
T2 CHECK DEPLOYABLE STEERING COLUMN 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: Deployable Steering Column C2318.
- 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 voltage between deployable steering column:
- C2318-1, circuit CR139 (VT/WH), harness side and ground.
- C2318-2, circuit RR139 (YE), harness side and ground.




- Is voltage present on either circuit?

Yes
REPAIR circuit CR139 (VT/WH) or RR139 (YE). GO to T5.

No
GO to T3.

-------------------------------------------------
T3 CONFIRM THE 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.

- Ignition OFF.
- Depower the SRS. Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.
- Connect: Deployable Steering Column C2318.
- 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 B2985 retrieved on-demand during self-test?

Yes
INSTALL a new RCM. REFER to Restraints Control Module (RCM) Service and Repair. GO to T5.

No
CHECK for causes of the intermittent fault. 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 T5.

-------------------------------------------------
T4 CHECK FOR AN INTERMITTENT FAULT


- Enter the following diagnostic mode on the scan tool: Self Test - RCM .
- Was DTC B2985 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 T2.

No
CHECK for causes of the intermittent fault. 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 T5.

-------------------------------------------------
T5 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.
- Are any RCM and/or OCSM DTCs 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 CMDTCs. PROVE OUT the SRS. Repair is complete. RETURN the vehicle to the customer.

-------------------------------------------------

pro multis · About Operation CHARM