brake light MAZDA MIATA 1991 Factory Service Manual

ANTI-LOCK BRAKE SYSTEM
1988-91 BRAKES Mazda Anti-Lock Brake System
DESCRIPTION
The Anti-Lock Brake System (ABS) control unit senses reductions in front and rear wheel speed, and modulates
hydraulic pressure to the brakes to prevent wheel lock-up. The ABS consists of a hydraulic unit, 4 wheel speed
sensors and sensor rotors, valve relay, motor relay, pump motor, and ABS control unit. An ANTI-LOCK
warning light is located on the instrument panel. See Fig. 1
thru Fig. 3 .
Fig. 1: Locating Motor Relay & Valve Relay

Courtesy of MAZDA MOTORS CORP.

1991 Mazda MX-5 Miata
ANTI-LOCK BRAKE SYSTEM 1988-91 BRAKES Mazda Anti-Lock Brake System

1991 Mazda MX-5 Miata
ANTI-LOCK BRAKE SYSTEM 1988-91 BRAKES Mazda Anti-Lock Brake System
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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
Microsoft
Sunday, July 05, 2009 2:17:31 PMPage 3 © 2005 Mitchell Repair Information Company, LLC.

Fig. 7: Locating JC-02 Connector
Courtesy of MAZDA MOTORS CORP.
ANTI-LOCK WARNING LIGHT
Operational Test (Miata)
1. Start engine, and observe ANTI-LOCK light. Light should illuminate for a few seconds. If light does not
illuminate as described, remove instrument cluster. Connect 12 volts to terminal 2k of instrument cluster.
See Fig. 8
. Using a jumper wire, connect terminal 1K of instrument cluster to ground. ANTI-LOCK light
should illuminate. If light does not illuminate, check bulb. If bulb is okay, check meter fuse and wiring
harness.
2. Install instrument cluster, and recheck warning light operation. If light still does not illuminate for a few
seconds, check wiring harness between ANTI-LOCK light and control unit and between ANTI-LOCK
light and hydraulic unit. Check operation of hydraulic unit valve relay.
Operational Test (RX7)

1991 Mazda MX-5 Miata
ANTI-LOCK BRAKE SYSTEM 1988-91 BRAKES Mazda Anti-Lock Brake System
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1. Start engine, and observe ANTI-LOCK light. Light should illuminate for a few seconds. If light does not
illuminate as described, remove clock and bezel assembly from dashboard. Slide warning and clock unit
from instrument panel. Connect terminal "E" to ground. See Fig. 9
. ANTI-LOCK light should illuminate.
If light does not illuminate, check bulb. If bulb is okay, check meter fuse and wiring harness.
2. Install instrument cluster, and recheck warning light operation. If light still does not illuminate for a few
seconds, check wiring harness between ANTI-LOCK light and control unit, and ANTI-LOCK light and
hydraulic unit. Check operation of hydraulic unit valve relay.
Operational Test (929)
1. Start engine, and observe ANTI-LOCK light. Light should illuminate for a few seconds. If light does not
illuminate as described, remove instrument cluster. Connect 12 volts to terminal "J" of instrument cluster
connector I-06. See Fig. 10
. Using a jumper wire, connect terminal "E" of instrument cluster connector I-
08 to negative ground. ANTI-LOCK light should illuminate. If light does not illuminate, check bulb. If
bulb is okay, check meter fuse and wiring harness.
2. Install instrument cluster, and recheck warning light operation. If light still does not illuminate for a few
seconds, check wiring harness between ANTI-LOCK light and control unit and between ANTI-LOCK
light and hydraulic unit. Check operation of hydraulic unit valve relay.
Fig. 8: Testing ANTI
-LOCK Warning Light (Miata)
Courtesy of MAZDA MOTORS CORP.

1991 Mazda MX-5 Miata
ANTI-LOCK BRAKE SYSTEM 1988-91 BRAKES Mazda Anti-Lock Brake System
Microsoft
Sunday, July 05, 2009 2:17:31 PMPage 9 © 2005 Mitchell Repair Information Company, LLC.

Fig. 9: Testing ANTI-LOCK Warning Light (RX7)
Courtesy of MAZDA MOTORS CORP.

1991 Mazda MX-5 Miata
ANTI-LOCK BRAKE SYSTEM 1988-91 BRAKES Mazda Anti-Lock Brake System
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Sunday, July 05, 2009 2:17:31 PMPage 10 © 2005 Mitchell Repair Information Company, LLC.

Fig. 10: Testing ANTI-LOCK Warning Light (929)
Courtesy of MAZDA MOTORS CORP.
STOPLIGHT SWITCH
Continuity Test
Disconnect stoplight switch connector. Using a DVOM, check continuity between Green or Green/White wire
and White/Green wire with brake pedal depressed. Ensure continuity exists. Release pedal, and note reading on
DVOM. Continuity should not be present. If continuity is not as specified, replace switch.
FRONT & REAR VALVES
Resistance Test (Miata)
1. Disconnect hydraulic unit 12-pin connector. Using a DVOM, measure resistance between the following
wires: Yellow/Green wire and Black wire; Brown wire and Black wire; Black/White wire and Black wire.
Resistance should be 1-1.2 ohms in each measurement.
2. If resistance is not as specified, replace hydraulic unit. If resistance is as specified, check wiring harness
between ABS control unit and hydraulic unit.
Resistance Test (RX7 & 929)

1991 Mazda MX-5 Miata
ANTI-LOCK BRAKE SYSTEM 1988-91 BRAKES Mazda Anti-Lock Brake System
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Fig. 16: Test 4 System Voltage Test
Courtesy of MAZDA MOTORS CORP.
TEST 5A. ANTI-LOCK LIGHT TEST
Fig. 17: Test 5A. Anti
-Lock Light Test
Courtesy of MAZDA MOTORS CORP.
TEST 5B. BRAKE LIGHT SWITCH TEST

1991 Mazda MX-5 Miata
ANTI-LOCK BRAKE SYSTEM 1988-91 BRAKES Mazda Anti-Lock Brake System
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Fig. 18: Test 5B. Brake Light Switch Test
Courtesy of MAZDA MOTORS CORP.
TEST 5C. PUMP TEST

1991 Mazda MX-5 Miata
ANTI-LOCK BRAKE SYSTEM 1988-91 BRAKES Mazda Anti-Lock Brake System
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Courtesy of MAZDA MOTORS CORP.
ADJUSTMENTS
PEDAL FREE PLAY
Depress pedal several times to release vacuum. Pedal free play should be .16-.28" (4-7 mm).
PEDAL HEIGHT & STOPLIGHT SWITCH
1. Released pedal height is measured from carpet surface on vertical portion of firewall to pedal pad center.
Disconnect stoplight switch. Move switch away from pedal. Adjust brake pedal push rod until correct
released pedal height is obtained. See BRAKE PEDAL HEIGHT SPECIFICATIONS TABLE.
2. Adjust pedal free play. See PEDAL FREE PLAY under ADJUSTMENTS. Tighten push rod lock nut.
Rotate stoplight switch until it contacts pedal, then rotate an additional 1/2 turn. Tighten stoplight switch
lock nut. Reconnect stoplight switch.
3. The applied pedal height is measured from angled portion of firewall (without carpet) to pedal pad center.
Start engine. Depress brake pedal with 132-lb. (60 kg) pressure.
4. Measure the applied pedal height. If distance is not as specified, check brake adjustment, or check for air
in system. See BRAKE PEDAL HEIGHT SPECIFICATIONS TABLE.
BRAKE PEDAL HEIGHT SPECIFICATIONS
TORQUE SPECIFICATIONS
TORQUE SPECIFICATIONS
Application(1) In. (mm)
Pedal Released
Miata & 9296.7-7.1 (171-181)
RX77.2-7.4 (184-189)
Pedal Applied
Miata & 9293.7 (95)
RX73.9 (100)
(1)Minimum height.
ApplicationFt. Lbs. (N.m)
Brake Caliper Mounting Bolts
Miata36-51 (49-69)
RX7
Front58-72 (79-98)
Rear33-40 (45-54)
929
Front61-69 (83-94)

1991 Mazda MX-5 Miata
ANTI-LOCK BRAKE SYSTEM 1988-91 BRAKES Mazda Anti-Lock Brake System
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Fig. 3: Moving Quadrant on Rear Brake Adj. (Typical Protege & 323)
Courtesy of MAZDA MOTORS CORP.
2. Push adjusting lever toward backing plate. Install brake drum. Install new lock nut, and secure by
crimping. Operate parking brake a few times to reset adjuster. Adjust parking brake.
Navajo
1. Raise and support rear of vehicle. If drums are installed on vehicle, remove cover from adjusting hole at
bottom of brake backing plate. Turn adjusting screw with a brake adjusting tool until shoes drag against
brake drum and lock drum.
2. When shoes are against drum, loosen adjusting screw an additional 10-12 notches so drum rotates freely.
If drum does not rotate freely, remove wheel and drum and vacuum dust and dirt from linings. Use
sandpaper and remove rust from points where shoes touch backing plate. Apply a light coating of
molybdenum grease to brake shoe-to-backing plate contact points. Install wheel and drum and adjust
shoes.
3. To adjust brakes with rear drums removed, first clean all rust and dirt on points where shoes touch
backing plate and apply a small amount of molybdenum grease to those areas. Use a brake shoe
adjustment gauge and adjust brakes to inside diameter of drum braking surface.
4. Reverse tool and adjust brake shoes until they touch gauge. Gauge contact points on shoes must be
parallel to vehicle with center line throu
gh center of axle. Hold automatic adjusting lever out of

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