Starter - Direct Drive: Diagnosis Mazda MX-5 NA

TROUBLE SHOOTING

Note. See TROUBLE SHOOTING - BASIC PROCEDURES article in the GENERAL INFORMATION section.

ON-VEHICLE TESTING

Note. Before testing, ensure battery is fully charged, battery cables and terminals are clean and tight and engine grounds are good.

CIRCUIT TESTING

If starter does not operate, check voltage at starter "S" terminal with ignition switch in START position (and clutch depressed on M/T). (Scheme 2) If voltage is greater than 8 volts, repair or replace as required. If voltage is less than 8 volts, check ignition switch, inhibitor switch (A/T), interlock switch (M/T) and wiring.

Scheme 2

NO-LOAD TEST

Connect fully-charged 12-volt battery, voltmeter and ammeter to starter. (Scheme 3) Using remote starter wires or jumper, engage solenoid. Starter should spin smoothly. Compare readings with specifications. See NO-LOAD TEST SPECIFICATIONS table. If voltage is less than specified or amperage is more than specified, disassemble and inspect starter components.

NO-LOAD TEST SPECIFICATIONS

Scheme 3

SOLENOID TEST

Note. Perform solenoid tests with starter assembled and field lead ("M" terminal wire) disconnected at the solenoid. (Scheme 3)

Solenoid Pull-In Test

Connect positive battery lead to solenoid "S" terminal and negative battery lead to starter body. (Scheme 3) Starter pinion drive gear should extend quickly and maintain this position. If starter pinion drive gear does not extend, replace solenoid.

Solenoid Return Test

Connect positive battery lead to solenoid "M" terminal and ground negative battery lead to starter body. (Scheme 3) Using screwdriver, pry overrunning clutch pinion drive outward. Release screwdriver and ensure overrunning clutch pinion drive returns to original position.

Solenoid Hold-In Test

Remove solenoid from starter. Connect positive battery lead to solenoid "S" terminal and negative battery lead to solenoid case. Push plunger into switch. If plunger stays in solenoid, hold-in windings are okay. If plunger does not stay in solenoid, replace solenoid.

ARMATURE TEST

1. Place armature in growler. Turn on growler and hold a piece of hacksaw blade over armature. Slowly rotate armature. If hacksaw blade is attracted to core or if it vibrates, replace armature.
2. Remove armature from growler. Using an ohmmeter, check continuity between commutator and core. If continuity exists, replace armature. Check continuity between commutator and shaft. If continuity exists, replace armature.
3. Check continuity between each commutator segment. If an open exists between any 2 segments, replace armature.

COMMUTATOR TEST

1. Clean surface and polish with No. 400 sandpaper if required. If surface is scored, out of round or pitted, turn commutator in a lathe.
2. Maximum commutator runout and minimum diameter of commutator must not exceed specification after turning. See COMMUTATOR SPECIFICATIONS table.
3. Commutator mica undercut depth should be .020 -.030" (.50 -.80 mm). Minimum mica undercut depth is .008" (.20 mm). If not within specification, undercut to standard depth.

COMMUTATOR SPECIFICATIONS

BRUSH TEST

1. Connect ohmmeter lead to positive brush holder and other lead to negative brush holder. If continuity exists, brush holder assembly is shorted and must be replaced.
2. Check brush length. Standard brush length is .67" (17.0 mm). Minimum brush length is .45" (11.5 mm). If length is less than specified, replace brushes.
3. Using brush spring scale, measure spring tension. Tension should be greater than 2 lbs. (0.9 kg). Tension for a NEW spring should be 3.1-5.7 lbs. (1.4-2.6 kg). Ensure brushes move freely in holders.

FIELD WINDING TEST

1. Connect one ohmmeter lead to field coil lead ("M" terminal lead). Connect other lead to soldered portion of brush lead. If continuity does not exist, repair or replace field coil.
2. Check field coil for shorts to ground by connecting ohmmeter lead to field coil lead. Connect other lead to field coil housing. If continuity exists, repair or replace field coil.