1997 MAZDA MX-5 Factory Repair Manual

GENERATOR & REGULATOR
1997 STARTING & CHARGING SYSTEMS Mazda - Generators & Regulators
DESCRIPTION & OPERATION
Generator is a conventional 3-phase, self-rectifying type with 6 diodes (3 positive and 3 negative) that rectify
current. Internal regulator is solid-state type.
ADJUSTMENTS
BELT DEFLECTION
Measure belt deflection in center of longest pulley-to-pulley span. See BELT DEFLECTION
SPECIFICATIONS table. If belt deflection is not as specified, adjust as necessary.
BELT DEFLECTION SPECIFICATIONS
TROUBLE SHOOTING
TROUBLE SHOOTING PRECAUTIONS
Observe the following precautions when trouble shooting or testing charging system:
Obtain code number and deactivate audio anti-theft system before disconnecting battery (if equipped).
DO NOT reverse battery cable connections. Rectifier will be damaged.
DO NOT use high voltage type testers.
Battery voltage should always exist at generator terminal "B".
DO NOT ground generator terminal "L" while engine is running.
DO NOT start engine with connector disconnected from generator terminals "L" and "S".
DO NOT apply battery voltage to terminal "L".
ON-VEHICLE TESTING
* PLEASE READ FIRST *
Application(1) Deflection - In. (mm)
New Belt0.22-0.28 (5.5-7.0)
Used Belt0.24-0.30 (6.0-7.5)
(1)With 22 lbs. (10 kg) applied to belt.
NOTE: See TROUBLE SHOOTING article in GENERAL INFORMATION.

1997 Mazda MX-5 Miata
GENERATOR & REGULATOR 1997 STARTING & CHARGING SYSTEMS Mazda - Generators & Regulators

1997 Mazda MX-5 Miata
GENERATOR & REGULATOR 1997 STARTING & CHARGING SYSTEMS Mazda - Generators & Regulators
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GENERATOR OUTPUT
1. Connect an ammeter (100-amp minimum) in-line between generator terminal "B" connector and terminal
"B" of wiring harness connector. See Fig. 1
. Turn headlights and all accessories on. Depress brake pedal.
Operate engine at 2500-3000 RPM.
2. Measure and record generator output. See GENERATOR MAXIMUM RATED OUTPUT
table. If
amperage is as specified, go to next step. If amperage is not as specified, repair or replace generator.
3. Turn off headlights and all accessories. Release brake pedal. Operate engine at 2500-3000 RPM and
measure amperage under no-load condition. No-load amperage should be 5 amps or greater. If amperage
is as specified, go to next step. If amperage is not as specified, repair or replace generator.
4. Operate engine at 2500-3000 RPM. Measure voltage between ground and terminals "S" and "L". If 14.1-
14.7 volts does not exist, repair or replace generator. If 14.1-14.7 volts exists, generator output is okay.
GENERATOR MAXIMUM RATED OUTPUT NOTE: Check generator wiring harness connections and drive belt tension. Battery
must be fully charged before testing. Wait at least 30 seconds after starting
engine before measuring system voltage.
CAUTION: Ensure generator terminal "B" does not contact ground.
ApplicationAmps
A/T70
M/T65

1997 Mazda MX-5 Miata
GENERATOR & REGULATOR 1997 STARTING & CHARGING SYSTEMS Mazda - Generators & Regulators
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Fig. 1: Identifying Generator Terminals
Courtesy of MAZDA MOTORS CORP.
BENCH TESTING

1997 Mazda MX-5 Miata
GENERATOR & REGULATOR 1997 STARTING & CHARGING SYSTEMS Mazda - Generators & Regulators
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RECTIFIER/DIODE ASSEMBLY
1. Using an ohmmeter, check continuity of each diode in both directions (polarity). See Fig. 2
thru Fig. 4. If
diode shows high resistance in one direction and low resistance in other direction, diode is okay.
2. If diode shows low resistance in both directions, diode is shorted. If diode shows high resistance in both
directions, diode is open. If any diode is defective, replace rectifier assembly.
ROTOR & SLIP RINGS
Measure resistance between rotor slip ring contacts. See Fig. 5
thru Fig. 9 . If resistance is not within
specification, replace rotor. See ROTOR RESISTANCE SPECIFICATIONS
table. Check continuity
between individual slip rings and rotor core/shaft. If continuity exists, replace rotor.
ROTOR RESISTANCE SPECIFICATIONS
STATOR
Check continuity between stator coil leads and stator core. See Fig. 5
thru Fig. 9 . If continuity exists, replace
stator. Check continuity between leads of stator coil. If continuity does not exist, replace stator.
BRUSHES
Replace brushes if worn to limit line. See Fig. 5
thru Fig. 9 . Replace brush springs if corroded. For brush
replacement procedure, see OVERHAUL
.
Application(1) Ohms
Miata3.5-4.5
(1)If continuity does not exist, replace rotor.

1997 Mazda MX-5 Miata
GENERATOR & REGULATOR 1997 STARTING & CHARGING SYSTEMS Mazda - Generators & Regulators
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Fig. 2: Testing Rectifier Diodes
Courtesy of MAZDA MOTORS CORP.

1997 Mazda MX-5 Miata
GENERATOR & REGULATOR 1997 STARTING & CHARGING SYSTEMS Mazda - Generators & Regulators
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Fig. 3: Rectifier Schematic
Courtesy of MAZDA MOTORS CORP.

1997 Mazda MX-5 Miata
GENERATOR & REGULATOR 1997 STARTING & CHARGING SYSTEMS Mazda - Generators & Regulators
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Fig. 4: Rectifier Continuity Test Chart
Courtesy of MAZDA MOTORS CORP.
Fig. 5: Testing Generator Stator, Rotor & Brushes

Courtesy of MAZDA MOTORS CORP.

1997 Mazda MX-5 Miata
GENERATOR & REGULATOR 1997 STARTING & CHARGING SYSTEMS Mazda - Generators & Regulators
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Fig. 6: Checking Stator Winding Continuity
Courtesy of MAZDA MOTORS CORP.

1997 Mazda MX-5 Miata
GENERATOR & REGULATOR 1997 STARTING & CHARGING SYSTEMS Mazda - Generators & Regulators
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