Mazda MX-5 Miata (1997+). Manual - part 35

 

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Mazda MX-5 Miata (1997+). Manual - part 35

 

 

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 Belt

0.22-0.28 (5.5-7.0)

Used Belt

0.24-0.30 (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

  

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.

Application

Amps

A/T

70

M/T

65

 

1997 Mazda MX-5 Miata 

GENERATOR & REGULATOR 1997 STARTING & CHARGING SYSTEMS Mazda - Generators & Regulators

  

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

  

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

Miata

3.5-4.5

(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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