service MAZDA MIATA 1991 Factory Service Manual

AIR BAG RESTRAINT SYSTEM
MAZDA 1990-91 AIR BAGS
DESCRIPTION & OPERATION
The air bag restraint system, when used in conjunction with seat belt, provides increased protection for the
driver in a collision. The air bag restraint system consists of the following: AIR BAG warning light, air bag
module, clockspring connector, diagnostic module, crash sensors, back-up battery, and wiring harnesses.
The air bag is designed to deploy when rear safing sensor and at least one front impact sensor close in a
collision, and ignition switch is in the ON position. The back-up battery supplies current for the ignitor if the
vehicle battery or fuses fail during a collision. The diagnostic module monitors the air bag system for failures. I
f
any failures are detected by the module, the driver is warned of such failure(s) through the activation or flashing
of the AIR BAG warning light.
SERVICE PRECAUTIONS
Disable air bag system before servicing any air bag system or steering column component. See
DISABLING & ACTIVATING AIR BAG
SYSTEM
Wait about 10 MINUTES after disabling air bag system before servicing. Air bag system voltage is
maintained for about 10 MINUTES after system is disabled. Failure to wait 10 MINUTES before
servicing system may cause accidental air bag deployment and possible personal injury.
On Miata, obtain radio code number from customer and deactivate radio anti-theft function before
disconnecting battery.
Because of the critical system operating requirements, DO NOT service any air bag system component.
Corrections are made by replacement only.
DO NOT use an ohmmeter to check resistance of air bag module, as it may cause air bag deployment.
When carrying a live (undeployed) module, ensure trim cover is pointed away from your body. This
minimizes chance of injure in the event ofaccidental air bag deployment.
When placing a live air bag module on any surface, always face trim cover upward to reduce motion of
module if it is accidentally deployed.
If an open circuit is present, replace entire wiring harness. DO NOT attempt wire repair.
Impact sensors must always be installed with arrow marks facing front of vehicle. Also, check sensors for
cracks, defects or rust before installation. Replace impact sensor(s) if required.
Air bag system clockspring MUST be aligned in the neutral position, since its rotation ability is limited.
DO NOT turn steerin
g wheel or column after removal of steering gear. WARNING:To avoid injury from accidental air bag deployment, read and carefully
follow all WARNINGS and SERVICE PRECAUTIONS.
NOTE: The following precautions should be observed when working with air bag
systems.

1991 Mazda MX-5 Miata
AIR BAG RESTRAINT SYSTEM MAZDA 1990-91 AIR BAGS

1991 Mazda MX-5 Miata
AIR BAG RESTRAINT SYSTEM MAZDA 1990-91 AIR BAGS
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ADJUSTMENTS
CLOCKSPRING CENTERING
Set front wheels in straight-ahead position. Turn clockspring connector clockwise until it stops (do not force).
Return connector 2 3/4 turns counterclockwise. Rotate clockspring connector further, if necessary, to align
marks on connector and outer housing.
DISPOSAL PROCEDURES
DEPLOYED AIR BAG
Dispose deployed air bag module as you would any other part. Wear gloves and safety glasses when handling
air bag module.
SCRAPPED VEHICLE
1. Ensure vehicle is outside, and away from other vehicles and people. Open convertible top and doors.
Disconnect negative battery cable.
2. Ensure air bag module is firmly mounted to steering wheel. Remove knee protector and disconnect
Orange and Blue clockspring connectors at base of steering column. See Fig. 1
. Cut clockspring
connector Blue wires.
3. Connect 2 jumper wires (20 feet long) to cut clockspring wires. Connect other ends of wires to a 12-volt
battery to deploy air bag. Because of heat, wait 10 MINUTES before touching deployed air bag.
REMOVAL & INSTALLATION
CRASH SENSORS NOTE: Perform the following procedures when scrapping a vehicle with undeployed air
bag.
WARNING:Follow air bag service precautions to prevent accidentalair bag
deployment and personal injury. See SERVICE PRECAUTIONS.
NOTE: After component replacement, check system to ensure proper operation. See
SYSTEM OPERATION CHECK.
NOTE: Crash sensor orientation and mounting is important for proper operation. All
sensors must be positioned so that arrow points forward. If there is sheet metal
damage near sensor mounting point, inspect body structure at sensor
mounting point for deformation. If damaged, restore to original shape. Ensure
sensor mounting bolts or nuts are tightened to specification. See TORQUE
SPECIFICATIONS table.

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AIR BAG RESTRAINT SYSTEM MAZDA 1990-91 AIR BAGS
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Removal (Front Impact Sensors)
1. Before proceeding, follow air bag service precautions. See SERVICE PRECAUTIONS. Disable air bag
system. See DISABLING & ACTIVATING AIR BAG SYSTEM.
2. Front impact sensors are located in left front and right front of vehicle. See Fig. 2
or Fig. 3 . To remove
left or right sensor, remove wheelwell undercover, and disconnect connector(s). Remove retaining clips
and bolts. Remove sensor(s).
Fig. 2: Locating Crash Sensors (Miata)

Courtesy of MAZDA MOTORS CORP.

1991 Mazda MX-5 Miata
AIR BAG RESTRAINT SYSTEM MAZDA 1990-91 AIR BAGS
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Fig. 3: Locating Crash Sensors (RX7 Convertible)
Courtesy of MAZDA MOTORS CORP.
Installation
To install, reverse removal procedure. Position sensor with arrow toward front of vehicle. Tighten mounting
bolts to specification. See TORQUE SPECIFICATIONS table. Reactivate air bag system. See DISABLING &
ACTIVATING AIR BAG SYSTEM. Check AIR BAG indicator light to ensure system is functioning properly.
See SYSTEM OPERATION CHECK.
Removal (Rear Safing Sensor)
Before proceeding, follow air bag service precautions. See SERVICE PRECAUTIONS. Disable air bag system.
See DISABLING & ACTIVATING AIR BAG SYSTEM. Rear safing sensor is located under center of
instrument panel. Remove instrument panel. Locate and disconnect safing sensor connectors. See Fig. 2
or Fig.
3 . Remove sensor and cover.
Installation
To install, reverse removal procedure. Position sensor with arrow toward front of vehicle. Tighten mounting
nuts to specification. See TORQUE SPECIFICATIONS table. Reactivate air ba
g system. See DISABLING &
CAUTION: A double-lock mechanism is used on clockspring connectors. DO NOT
use excessive force when disconnecting connectors, as damage to
connector may occur.

1991 Mazda MX-5 Miata
AIR BAG RESTRAINT SYSTEM MAZDA 1990-91 AIR BAGS
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ACTIVATING AIR BAG SYSTEM. Check AIR BAG indicator light to ensure system is functioning properly.
See SYSTEM OPERATION CHECK.
AIR BAG MODULE
Removal & Installation
1. Before proceeding, follow air bag service precautions. See SERVICE PRECAUTIONS. Disable air bag
system. See DISABLING & ACTIVATING AIR BAG SYSTEM.
2. Air bag module is located on center of steering wheel. See Fig. 4
or Fig. 5 . Remove air bag module nuts
and remove module from steering wheel. To install, reverse removal procedure. Tighten air bag module
mounting nuts to specification. See TORQUE SPECIFICATIONS table. Reactivate air bag system. See
DISABLING & ACTIVATING AIR BAG SYSTEM. Check AIR BAG indicator light to ensure system is
functioning properly. See SYSTEM OPERATION CHECK.
Fig. 4: Identifying Air Bag System Components (Miata)

Courtesy of MAZDA MOTORS CORP.

1991 Mazda MX-5 Miata
AIR BAG RESTRAINT SYSTEM MAZDA 1990-91 AIR BAGS
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Removal
1. Before proceeding, follow air bag service precautions. See SERVICE PRECAUTIONS. Disable air bag
system. See DISABLING & ACTIVATING AIR BAG SYSTEM.
2. Clockspring connector assembly is located under steering wheel, in steering column. See Fig. 4
or Fig. 5.
Remove air bag module. See AIR BAG MODULE. Remove steering wheel nut and remove steering
wheel with steering wheel puller. Remove column covers. Remove screws. Remove clockspring
connector and combination switch as an assembly.
DIAGNOSTIC MODULE & BACK-UP BATTERY
Removal & Installation
1. Before proceeding, follow air bag service precautions. See SERVICE PRECAUTIONS. Disable air bag
system. See DISABLING & ACTIVATING AIR BAG SYSTEM.
2. Diagnostic module and back-up battery is located under left side of instrument panel. See Fig. 4
or Fig.
5 . Disconnect diagnostic module and back-up battery connectors. Remove nuts. Remove diagnostic
module and back-up battery as an assembly. To install, reverse removal procedure. After diagnostic
module and back-up battery are installed, reactivate air bag system. See DISABLING & ACTIVATING
AIR BAG SYSTEM. Check AIR BAG indicator light to ensure system is functioning properly. See
SYSTEM OPERATION CHECK.
SYSTEM OPERATION CHECK
Turn ignition switch to the ON or START position. AIR BAG warning light in instrument cluster should
illuminate for approximately 6 seconds then go out. This indicates that the air bag system is functioning
properly. If any of the following conditions exists, air bag system is malfunctioning and needs repair.
AIR BAG warning light does not illuminate as described.
AIR BAG warning light stays on for more than 6 seconds.
AIR BAG warning light illuminates while driving.
If air bag system components are replaced for any reason, air bag system must be checked for proper function
after repair. Turn ignition on. AIR BAG warning light should illuminate for approximately 6 seconds then go
out. If AIR BAG warning light does not illuminate as described, air bag system is malfunctioning and needs
repair. If warning light functions as described, check horn operation. If horn does not sound, remove air bag
module and check air bag module and horn switch connections. Always follow service precautions and
deactivate air bag system before performing repairs. See DISABLING & ACTIVATING AIR BAG
SYSTEM .
WIRE REPAIR
DO NOT repair air bag system wiring. If air bag harness connectors are faulty, replace faulty wiring harness.
TORQUE SPECIFICATIONS

1991 Mazda MX-5 Miata
AIR BAG RESTRAINT SYSTEM MAZDA 1990-91 AIR BAGS
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TORQUE SPECIFICATIONS
DIAGNOSIS & TESTING
SELF-DIAGNOSTIC SYSTEM
Trouble Shooting
AIR BAG warning light flashes are used to diagnose air bag system. The number of warning light flashes
depends on the type of fault being detected. Codes are prioritized so that if 2 or more faults are present, the
highest test-priority fault indication will remain until corrected.
Warning Light Does Not Illuminate
Check for blown fuses, burned-out bulb, disconnected diagnostic module, or open circuit between warning light
and diagnostic module.
Warning Light Flashes Or Remains On
Check code output of AIR BAG warning light. See AIR BAG FLASH CODES table.
AIR BAG FLASH CODES
ApplicationFt. Lbs. (N.m)
Air Bag Module Nuts12-15 (16-20)
Steering Wheel Nut29-36 (39-49)
INCH Lbs. (N.m)
Front Impact Sensor Bolts78-113 (9-13)
Rear Safing Sensor Nuts
Miata78-113 (9-13)
RX761-87 (7-10)
WARNING:Follow air bag service precautions to prevent accidentalair bag
deployment and personal injury. See SERVICE PRECAUTIONS.
NOTE: After component replacement, check system to ensure proper operation. See
SYSTEM OPERATION CHECK.
PriorityFlash CodeCause/Diagnosis
1Remains OnFaulty Diagnostic Module
Poor Connection Of Diagnostic
Module Connector (See
DIAGNOSTIC TEST NO. 1)
2Flashes 3 TimesOpen Circuit
Poor Connection Of Power Source

1991 Mazda MX-5 Miata
AIR BAG RESTRAINT SYSTEM MAZDA 1990-91 AIR BAGS
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OPERATION
Under normal driving conditions, the anti-lock brake system functions as a standard brake system. When
vehicle speed reaches 3.8 MPH, the ABS system will diagnose pump motor by briefly operating motor. Pump
motor operation may be heard inside vehicle.
The Electronic Control Unit (ECU) controls ABS by detecting speed sensor signals and activating solenoid
valve in hydraulic unit. Control unit also controls pump motor and self-diagnostic function. If a problem in the
ABS system is detected, ABS system functions as a conventional brake system. The ANTI-LOCK brake
warning light will also come on.
With detection of wheel lock-up, short pedal pulsations, occurring in rapid succession, will be felt in brake
pedal and steering wheel. Vehicle body may also vibrate slightly. These conditions are normal. Pedal pulsation
will continue until there is no longer a need for anti-lock function or until vehicle is stopped.
ANTI-LOCK BRAKE SAFETY PRECAUTIONS
NEVER open a bleeder valve or loosen a hydraulic line while ABS is pressurized.
NEVER disconnect or reconnect any electrical connectors while ignition is on. Damage to ABS control
unit may result.
DO NOT attempt to bleed hydraulic system without first referring to the appropriate article.
Only use specially designed brake hoses/lines on ABS-equipped vehicles.
DO NOT tap on speed sensor components (sensor, sensor rings). Speed rings must be pressed, NOT
hammered into hubs. Striking these components can cause demagnetization or a loss of polarization,
affecting the accuracy of the speed signal returning to the ABS control unit.
DO NOT mix tire sizes. Increasing the width, as long as tires remain close to the original diameter, is
acceptable. Rolling diameter must be identical for all 4 tires. Some manufacturers recommend tires of the
same brand, style and type. Failure to follow this precaution may cause inaccurate wheel speed readings.
DO NOT contaminate speed sensor components with grease. Only use recommended anti-corrosion
coating.
When speed sensor components have been removed, ALWAYS check sensor-to-ring air gaps when
applicable. These specifications can be found in each appropriate article.
ONLY use recommended brake fluids. DO NOT use silicone brake fluids in an ABS-equipped vehicle.
When installing transmitting devices (CB's, telephones, etc.) on ABS-equipped vehicles, DO NOT locate
the antenna near the ABS control unit (or any control unit).
Disconnect all on-board computers, when using electric welding equipment. CAUTION: See ANTI-LOCK BRAKE SAFETY PRECAUTIONS below.
WARNING:Refer to appropriate Anti-Lock Brakes (ABS) article for description,
operation, depressurizing, testing, system bleeding, trouble shooting and
system service. Failure to depressurize ABS could lead to physical injury.

1991 Mazda MX-5 Miata
ANTI-LOCK BRAKE SYSTEM 1988-91 BRAKES Mazda Anti-Lock Brake System
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1. Disconnect hydraulic unit 12-pin connector. Using a DVOM, measure resistance between Green/Black
and Yellow/Red wires, Green/White and Yellow/Red wires and Yellow and Yellow/Red wires.
Resistance should be 1-1.2 ohms in each measurement.
2. If resistance if not as specified, replace hydraulic unit. If resistance is as specified, check wiring harness
between ABS control unit and hydraulic unit.
HYDRAULIC UNIT
Only serviceable parts of hydraulic unit are motor relay and valve relay. If other parts of unit malfunction,
replace hydraulic unit assembly.
MOTOR RELAY
Continuity Tests
1. Disconnect negative battery cable. Remove motor relay from hydraulic unit. Ensure continuity exists
between terminals "B" and "C" of motor relay. See Fig. 11
. Connect 12 volts to terminal "C", and ground
terminal "B". Ensure continuity exists between terminals "A" and "D".
2. Replace relay if continuity is not as specified. If continuity is as specified, check wiring harness between
motor relay and ABS control unit fuse (60 amps).
Fig. 11: Identifying Motor & Valve Relay Terminals

Courtesy of MAZDA MOTORS CORP.
PUMP MOTOR
Continuity Test (Miata)

1991 Mazda MX-5 Miata
ANTI-LOCK BRAKE SYSTEM 1988-91 BRAKES Mazda Anti-Lock Brake System
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Fig. 1: Adjusting Brake Booster Push Rod (Navajo)
Courtesy of FORD MOTOR CO.
2. Place gauge against master cylinder mounting surface of booster. Adjust push rod screw by turning it
until end of screw just touches inner edge of gauge slot.
REAR BRAKE SHOES
B2200 & B2600i 2WD
NOTE: Self-adjusting rear brakes only require manual adjustment when brake shoe is
replaced or operating lever is moved during service operations.

1991 Mazda MX-5 Miata
BRAKE SYSTEM 1991 BRAKES Mazda Brake System
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