torque FORD MUSTANG 2003 Workshop Manual

Pinpoint Test B: LFC 21/DTC B1921 —
RCM Bracket Ground Resistance High
Normal Operation
WARNING: The tightening torque of the restraints control module (RCM) retaining bolts is
critical for proper air bag supplemental restraint system (SRS) operation. Refer to Restraints Control Module (RCM) in this section for correct torque values.
The restraints control module (RCM) monitors the resistance between the ground connections at its
housing and the reference ground at pin 21. If the RCM detects a resistance greater than 100 ohms, it
will store a diagnostic trouble code (DTC) B1921 in memory and flash a lamp fault code (LFC) 21 (or
higher priority code if one exists) on the air bag indicator.
Possible Causes
High resistance between the RCM housing ground and pin ground can be caused by:
zincorrect seating of the RCM retaining bolts.
z incorrect tightening torque of the RCM retaining bolts.
z high resistance on RCM logic ground circuit 397 (BK/WH).
PINPOINT TEST B: LFC 21/DTC B1921 — RCM BRACKET GROUND
RESISTANCE HIGH section for
pinpoint test
direction.
No
RECONNECT the
system.
REACTIVATE the
system. PROVE
OUT the system.
REFER to
Air Bag Supplemental
Restraint System
(SRS) in this
section. CLEAR all
DTCs. Test Step Result / Action to Take
B1 CHECK FOR A HARD OR INTERMITTENT DTC
z
Key in OFF position.
z Connect the diagnostic tool. Scan Tool
z Key in ON position.
z Enter the following diagnostic mode on the diagnostic tool:
Retrieve/Clear Continuous DTCs.
z Retrieve and record any continuous DTCs for use later in
this pinpoint test.
z Enter the following diagnostic mode on the diagnostic tool:
On- Demand Self Test.
z Was DTC B1921 retrieved during the on- demand self Yes
This is a hard fault. 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
B2 .
No Klj . 5 ba
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test? This is an intermittent fault.
The fault condition is not
present at this time. GO to
B6
.
B2 INSPECT THE RCM MOUNTING, MOUNTING BRACKET
AND MOUNTING SURFACE z
Remove the RCM. Refer to Restraints Control Module (RCM) in the Removal and Installation portion of this
section.
z Visually inspect the RCM, mounting bracket and mounting
surface for damage, corrosion or dirt.
z Inspect the RCM mounting and make sure that the
retaining bolts are fully seated and tightened correctly.
Refer to Restraints Control Module (RCM) in the Removal
and Installation portion of this section for correct tightening
torque.
z Was a significant amount of corrosion or dirt found,
the RCM mounting bracket attached to the mounting
surface incorrectly or were the three RCM retaining
bolts not fully seated and tightened correctly? Yes
Make sure the RCM,
mounting bracket and
mounting surface are free of
damage, corrosion or dirt and
the three retaining bolts are
fully seated and correctly
tightened. Reattach the RCM
and mounting bracket to the
mounting surface. GO to
B7 .
No
GO to B3 .
B3 CHECK THE RCM HARNESS CONNECTION
z
Check the RCM harness connection.
z Is the RCM harness connector connected to the RCM
correctly? Yes
GO to
B4 .
No
ATTACH the RCM harness
connector correctly. GO to
B7 .
B4 CHECK THE VEHICLE CHASSIS GROUND
z
Measure the resistance between a known good chassis
ground and the mounting surface of the RCM.
z Is the resistance greater than 100 ohms? Yes
REPAIR the chassis
grounding system. GO to
B7 .
No
GO to B5 .
B5 CHECK THE GROUND CIRCUIT 397 (BK/WH) FOR AN
OPEN z
Key in OFF position.
z Disconnect: RCM C2041.
z Measure the resistance between RCM C2041 pin 21,
circuit 397 (BK/WH), harness side and a sheet metal
ground near the RCM.
z Is the resistance greater than 100 ohms? Yes
REPAIR the circuit. GO to
B7
.
No
INSTALL a new RCM. GO to
B7 .
B6 CHECK FOR AN INTERMITTENT FAULT
z
Refer to the continuous DTCs recorded during Step B1. Yes Klj . 6 ba
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GENERAL PROCEDURES
Weld Nut Repair
—"J" Nut, Restraints Control Module
(RCM)
WARNING: To avoid accidental deployment and possible personal injury, the backup
power supply must be depleted before repairing or replacing any front or side air bag
supplemental restraint system (SRS) components and before servicing, replacing, adjusting or
striking components near the front or side air bag sensors, such as doors, instrument panel,
console, door latches, strikers, seats and hood latches.
Please refer to the appropriate vehicle shop manual to determine location of the front air bag
sensors.
The side air bag sensors are located at or near the base of the B- pillar.
To deplete the backup power supply energy, disconnect the battery ground cable and wait at
least one minute. Be sure to disconnect auxiliary batteries and power supplies (if equipped).
NOTE: There are two procedures to repair a vehicle having missing restraints control module attaching
weld nut(s). Read both procedures before proceeding with the repair.
NOTE: If two or more weld nuts are missing, do not install the "J" nuts as outlined in this procedure.
Weld nuts must be installed as outlined in Weld Nut Repair — Missing Weld Nut, Restraints Control
Module (RCM).
NOTE: The following procedure applies to vehicles that have a rectangular hole in the sheet metal that
is in close proximity to the missing weld nut.
1. Obtain a "J" nut (part number N623332- S301) or any of the following optional "J" nuts (part
numbers: N623342- S101, N800854-S100, N800925- S100).
2. Obtain a 6 mm (0.24 in) grounding screw (part number N806327- S190) or equivalent.
3. Install the "J" nut through the rectangular hole in the sheet metal.
4. NOTE: Be sure the threaded portion of the "J" nut is aligned with the clearance hole in the sheet
metal.
Install the crash sensor.
5. Tighten the attaching screws to specification. For additional information, refer to Torque Specifications in this section.
SECTION 501-
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5. Secure the flatwasher so that it cannot be pulled off the end of the copper welding wire.
6. Pull the copper welding wire back through the clearance hole, allowing the weld nut and
flatwasher to follow the copper welding wire through.
7. Position the weld nut to the weld nut clearance hole, firmly pulling on the copper welding wire allowing the secured flatwasher to hold the weld nut in position.
8. Holding the weld nut securely in place and using a MIG welder, weld in four places around the edge of the weld nut.
9. Metal finish as required.
10. Verify the nut is securely in place.
11. Install the crash sensor.
12. Tighten the attaching screws to specification. For additional information, refer to Torque Specifications in this section. Klj . 2 ba
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GENERAL PROCEDURES
Weld Nut Repair —
Stripped Weld Nut, Restraints Control
Module (RCM)
WARNING: To avoid accidental deployment and possible personal injury, the backup
power supply must be depleted before repairing or replacing any front or side air bag
supplemental restraint system (SRS) components and before servicing, replacing, adjusting or
striking components near the front or side air bag sensors, such as doors, instrument panel,
console, door latches, strikers, seats and hood latches.
Please refer to the appropriate vehicle shop manual to determine location of the front air bag
sensors.
The side air bag sensors are located at or near the base of the B- pillar.
To deplete the backup power supply energy, disconnect the battery ground cable and wait at
least one minute. Be sure to disconnect auxiliary batteries and power supplies (if equipped).
1. Obtain an 8 mm (0.32 in) grounding screw (part number N802455- S190).
2. Drill out the internal threads of the stripped- out weld nut to 7.37 mm (0.29 in) using a letter "L"
size drill bit.
3. Position the crash sensor to the vehicle.
4. Install the 8 mm (0.32 in) grounding screw into the drilled- out weld nut.
5. Install the remaining attaching screws.
6. Tighten the attaching screws to specification. For additional information, refer to Torque Specifications in this section.
SECTION 501-
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and wait at least one minute. Be sure to disconnect auxiliary batteries and power
supplies (if equipped).
Disconnect the battery ground cable (14301) and wait at least one minute. For additional
information, refer to
Section 414 - 01 .
2. WARNING: To reduce the risk of serious personal injury, read and follow all
warnings, cautions, notes, and instructions in the supplemental restraint system
(SRS) deactivation/reactivation procedure.
Deactivate the supplemental restraint system (SRS). For additional information, refer to
Supplemental Restraint System (SRS) Deactivation and Reactivation in the General
Procedures portion of this section.
2. Remove the right hand restraints control module (RCM) bracket retaining bolt. 1. Position the carpet back at the right hand side of the instrument panel (I/P) center support bracket.
2. Remove the RCM bracket retaining bolt.
3. Remove the RCM with bracket. 1. Position the carpet back at the left hand side of the I/P center support bracket.
2. Disengage the RCM electrical connector locking clip.
3. Disconnect the RCM electrical connector.
4. Remove the two retaining bolts.
5. Remove the RCM with bracket.
Installation WARNING: To reduce the risk of serious personal injury, read and follow all warnings,
cautions and notes at the beginning of the removal procedure.
1. WARNING: The tightening torque of the air bag restraints control module (RCM) retaining bolts is critical for correct system operation. Klj . 2 ba
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SPECIFICATIONS
SECTION 502-
00: Frame and Body Mounting 2003 Mustang Workshop Manual Torque Specifications
Description Nm lb-
ft Engine mount nuts (3.8L engine) 115 85
Engine mount nuts (4.6L engine) 150 111
Front subframe lower bolts 90 66
Front subframe upper bolts 115 85
Front subframe brace bolts 41 30
Front subframe support, front and rear outboard bolts (convertible vehicles only) 63 46
Front subframe support, rear inboard bolts (convertible vehicles only) 30 22
HEGO connector bracket nut 47 35
Rear subframe bolts 103 76
Transmission support insulator to transmission extension housing bolts 70 52
Transmission support insulator-
to-rear engine support nut 70 52
Transmission support crossmember to transmission support member through bolts and
nuts 63 46 Klj . 1 ba
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REMOVAL AND INSTALLATION
Rear Subframe
Removal and Installation
CAUTION: Suspension fasteners are critical parts because they affect performance of vital
components and systems and their failure can result in major service expense. A new part with
the same part number must be installed if installation becomes necessary. Torque values must
be used as specified during reassembly.
1. Remove the rear coil springs. For additional information, refer to Section 204 - 02 .
2. Using the special tool, raise the rear subframe.
3. Remove and discard the rear subframe front bolts.
4. Using the special tool, lower and remove the rear subframe.
5. NOTE: Discard the old bolts and nuts. Do not reuse, install new bolts and nuts.
To install, reverse the removal procedure.
SECTION 502-
00: Frame and Body Mounting 2003 Mustang Workshop Manual Klj . 1 ba
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SIR Coil Assembly (Clockspring)Air Bag Restraint System
Slip Ring (Clockspring)Air Bag Restraint System; Steering Column Switches
SRS Control ModuleAir Bag Restraint System
Starter MotorStarters
Starter Interrupt RelayStarters
Starter SolenoidStarters
Starter RelayStarters
Steering Wheel Position SensorAnti-Lock Brakes
StoplightsExterior Lights
Stoplight SwitchEngine Performance; Cruise Control Systems;
Anti-Lock Brakes
Sun Roof ECUPower Sun Roof
Sun Roof MotorPower Sun Roof
Sun Roof Position SensorPower Sun Roof
TaillightsExterior Lights
Throttle Position (TP) SensorEngine Performance
Torque Converter Clutch Solenoid/SwitchEngine Performance
Traction Control SwitchAnti-Lock Brakes
Trailer Tow ConnectorExterior Lights
Trailer Tow RelayExterior Lights
Transmission/TransaxleEngine Performance
Transmission Control Module (TCM)Engine Performance; Starters
Transmission Range SensorStarters; Back-Up Lights; Engine Performance
Transmission Range SwitchBack-Up Lights; Engine Performance; Anti-Theft
System
Turn Signal FlasherExterior Lights
Turn Signal LightsExterior Lights
Twilight Sentinel SwitchHeadlight Systems; Daytime Running Lights
Vapor Canister Le ak Detection PumpEngine Performance
Vehicle Control Module (VCM)Engine Performance
Vehicle Dynamic ModuleElectronic Suspension
Vehicle Speed Control ServoCruise Control Systems
Vehicle Speed SensorData Link Connectors; Analog Instrument Panels;
Cruise Control Systems; Electronic Suspension
Voltage RegulatorGenerators & Regulators
Water-In-Fuel SensorEngine Performance; Analog Instrument Panels
Wheel Speed SensorsAnti-Lock Brakes
Window Timer ModulePower Convertible Top
Windshield Intermittent Wiper RelayWiper/Washer Systems
Windshield Washer MotorWiper/Washer Systems
Wiper MotorWiper/Washer Systems

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