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Ford Falcon. Manual - part 456

501-20b-39

Occupant Restraints — Passive

501-20b-39

DIAGNOSIS AND TESTING (Continued)

Test Step

Result / Action to Take

CHECK THE AIR BAG TONE WARNING INDICATOR

Connect Instrument Cluster Module C171b.

Yes

INSTALL a new RCM. Go to E6.

Key in ON position.

Measure the voltage at RCM C189a pin 22, circuit 609 (O).

INSTALL a new instrument cluster module. Go

Is the voltage greater than 10 volts?

to E6.

CHECK FOR AN INTERMITTENT FAULT

Yes

WARNING:

If the supplemental restraint system (SRS) is

Go to E2.

being serviced, the system must be deactivated and restraint system

diagnostic tools must be installed. Refer to Airbag and Safety Belt

CHECK for causes of an intermittent short to

Pretensioner Supplemental Restraint System (SRS) in this section.

ground or open on circuit 609 (O). ATTEMPT to

The airbag restraint system diagnostic tools must be removed and

recreate the hard fault by flexing the wire

the airbag modules reconnected when the system is reactivated to

harness and cycling the ignition key frequently.

avoid non-deployment in a collision, resulting in possible personal

REPAIR any intermittent concerns found. Go to

injury.

E6.

WARNING:

Never probe the connectors on the airbag

module. Doing so can result in airbag deployment, which can result in
personal injury.

WARNING:

The safety belt buckle pretensioner is a

pyrotechnic device. Never probe a pretensioner electrical connector.
Doing so could result in pretensioner or airbag deployment and could
result in personal injury.

WARNING:

Never probe the connectors on the side airbag

module. Doing so can result in side airbag deployment.

NOTE:

Diagnostics or repairs are not to be performed on a seat

equipped with a seat side airbag with the seat in the vehicle. Prior to
attempting to diagnose or repair a seat concern when equipped with a seat
side airbag, the seat must be removed from the vehicle and the restraint
system diagnostic tools must be installed in the seat side airbag electrical
connectors. The restraint system diagnostic tools must be removed
prior to operating the vehicle over the road.

NOTE:

After diagnosing or repairing an SRS, the restraint system

diagnostic tools must be removed before operating the vehicle over
the road.

NOTE:

After diagnosing or repairing a seat system, the restraint system

diagnostic tools must be removed before operating the vehicle over the
road.

NOTE:

The SRS must be fully operational and free of faults before

releasing the vehicle to the customer.

Key in OFF position.

Deactivate the system. Refer to Airbag and Safety Belt Pretensioner
Supplemental Restraint System (SRS) in the Diagnosis and Testing
portion of this section.

Enter the following diagnostic mode on the diagnostic tool:
On-Demand Self Test

Was DTC B 1892 retrieved during the on-demand self test?

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501-20b-40

Occupant Restraints — Passive

501-20b-40

DIAGNOSIS AND TESTING (Continued)

Test Step

Result / Action to Take

CHECK FOR ADDITIONAL DTCs

Refer to the continuous DTCs recorded during Step E1.

Yes

Do not clear any DTCs until all DTCs have been

Were any continuous DTCs retrieved during Step E1?

resolved. GO to the Restraints Control Module
(RCM) Diagnostic Trouble Code (DTC) Table in
this section for pinpoint test direction.

RECONNECT the system. REACTIVATE the
system. PROVE OUT the system. REFER to
Airbag and Safety Belt Pretensioner
Supplemental Restraint System (SRS)in this
section. CLEAR all DTCs.

Pinpoint Test F: LFC 14/DTC B1921 —

Airbag Diagnostic Monitor Ground Circuit

Open

Normal Operation

WARNING: The tightening torque of the

restraints control module (RCM) retaining bolts is

critical for correct airbag supplemental restraint

system (SRS) operation. REFER to Restraints

Control Module (RCM) in this section for correct

torque values.
NOTE: A resistance difference as low as 10 ohms can

set the LFC.
The restraints control module (RCM) monitors the

resistance between the ground connections at the

mounting bracket and the reference ground at C189a

pin 16, circuit 1203A (B/G). If the RCM detects a

difference in resistance, it will store diagnostic trouble

code (DTC) B1921 in memory and flash lamp fault

code (LFC) 14 (or higher priority code if one exists) on

the airbag indicator.

Possible Causes

A resistance difference between the RCM bracket

ground and harness ground can be caused by:

the RCM or RCM bracket is not securely

mounted.
damaged wiring, terminals, or connectors.
a faulted RCM.

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501-20b-41

Occupant Restraints — Passive

501-20b-41

DIAGNOSIS AND TESTING (Continued)

PINPOINT TEST F : LFC 14/DTC B1921 — AIR BAG DIAGNOSTIC MONITOR GROUND CIRCUIT OPEN

Test Step

Result / Action to Take

CHECK FOR A HARD OR INTERMITTENT DTC

Enter the following diagnostic mode on the diagnostic tool:

Yes

This is a hard fault. The fault condition is still

Retrieve Continuous DTCs

present. This fault cannot be cleared until it is

Retrieve and record any continuous DTCs for use later in this pinpoint corrected and the DTC is no longer retrieved

test.

during the on-demand self test.
Go to F2

Enter the following diagnostic mode on the diagnostic tool:
On-Demand Self Test

This is an intermittent fault. The fault condition is

Was DTC B1921 retrieved during the on-demand self test?

not present at this time.
Go to F5

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501-20b-42

Occupant Restraints — Passive

501-20b-42

DIAGNOSIS AND TESTING (Continued)

Test Step

Result / Action to Take

INSPECT THE RCM MOUNTING, MOUNTING BRACKET

AND MOUNTING SURFACE

Yes

WARNING:

If the supplemental restraint system (SRS) is

CLEAN, TIGHTEN bolts or REPAIR the

being serviced, the system must be deactivated and restraint system

mounting surface as necessary. REINSTALL the

diagnostic tools must be installed. Refer to Airbag and Safety Belt

RCM and mounting bracket to the mounting

Pretensioner Supplemental Restraint System (SRS) in this section.

surface.
Go to F6.

The airbag restraint system diagnostic tools must be removed and
the airbag modules reconnected when the system is reactivated to

avoid non-deployment in a collision, resulting in possible personal

Go to F3.

injury.

WARNING:

Never probe the connectors on the airbag

module. Doing so can result in airbag deployment, which can result in
personal injury.

WARNING:

The safety belt buckle pretensioner is a

pyrotechnic device. Never probe a pretensioner electrical connector.
Doing so could result in pretensioner or airbag deployment and could
result in personal injury.

WARNING:

Never probe the connectors on the side airbag

module. Doing so can result in side airbag deployment.

NOTE:

Diagnostics or repairs are not to be performed on a seat

NOTE:

After diagnosing or repairing an SRS, the restraint system

diagnostic tools must be removed before operating the vehicle over
the road.

NOTE:

After diagnosing or repairing a seat system, the restraint system

diagnostic tools must be removed before operating the vehicle over the
road.

NOTE:

The SRS must be fully operational and free of faults before

releasing the vehicle to the customer.

Key in OFF position.

Deactivate the system. Refer to Airbag and Safety Belt Pretensioner
Supplemental Restraint System (SRS) in the Diagnosis and Testing
portion of this section.

Inspect the RCM mounting and make sure that the retaining bolts are
fully seated and tightened correctly.

Remove the RCM. Refer to Restraints Control Module (RCM) in this
section.

Visually inspect the RCM, mounting bracket and mounting surface for
damage, corrosion or dirt.

Was a significant amount of corrosion or dirt found, the RCM
mounting bracket attached to the mounting surface incorrectly
or were the RCM bolts not fully seated and tightened correctly?

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