Alternator & Regulator Mercury Capri III

DESCRIPTION

The Mitsubishi alternator is an 85-amp, conventional 3-phase, self-rectifying unit, which contains 3 positive diodes and 3 negative diodes. The integral rear case-mounted regulator is solid-state and contains the brushes. A charge indicator light in the instrument panel indicates charging system malfunctions. (Scheme 1)

Scheme 1

BELT TENSION

BELT ADJUSTMENTS (Using Belt Tension Gauge Or Deflection Method) (1)

TROUBLE SHOOTING

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

ON-VEHICLE TESTING

Note. Inspect system thoroughly before testing. Check alternator wiring harness connections, drive belt tension and battery voltage. Ensure battery cables and engine ground cable are clean and tight. Wait at least 30 seconds after starting engine before measuring voltage.

Scheme 2

1. Start engine and verify charge indicator light goes out. If indicator does not go out, go to step 2). If indicator does go out, go to step 5). Turn engine off.
2. Turn ignition switch to ON position and with engine off. Check voltage readings at each terminal. See ALTERNATOR TERMINAL VOLTAGE table. (Scheme 2)
3. With engine running at normal curb idle recheck alternator terminal voltages. See ALTERNATOR TERMINAL VOLTAGE table. (Scheme 2) ALTERNATOR TERMINAL VOLTAGE Alternator Terminal Ign. ON/Eng. OFF Volts Engine At Idle Volts B+ Approximately 12 14.1-14.7 "L" Approximately 1 14.1-14.7 "S" Approximately 12 14.1-14.7 CAUTION: DO NOT ground "B+" terminal.
4. Check wiring harness between battery and B+ terminal if voltage check is okay. Check wiring harness if voltages are below specification. If wiring harness is good, service or replace alternator. (Scheme 2)
5. Using Rotunda Starting and Charging Tester (078-00005 VAT40), connect positive lead to alternator B+ terminal connector. Connect negative lead to B+ terminal wiring connector and set tester to ammeter function. (Scheme 3) Connect Rotunda Inductive Dwell-Tach-Volts Ohms Tester (059-000 10).
6. With engine running and all accessories and lights on, depress brake pedal. With engine speed of 2500-3000 RPM, alternator output should be 70 amps or more. If not, recheck belt tension. If belt tension is okay, service or replace alternator.

Scheme 3

ROTOR

Visually inspect rotor for stripped threads or damage at pulley end. Check for scored bearing surfaces, scuff marks on the pole fingers, or dirty or contaminated slip rings. Check resistance across rotor slip rings. If there is not 2-6 ohms resistance, replace rotor. Check resistance between individual slip rings and rotor shaft. Reading should be infinite. If resistance exists, rotor or slip ring is grounded. Replace rotor.

STATOR

Visually inspect stator for burned or discolored windings, scuff marks on the inside of stator frame, or damage to stator frame. Check resistance between stator leads and stator frame. Resistance should be infinite. Check continuity between leads of stator coil. There should be continuity in all three positions. An internal short between adjacent stator windings may not be detectable. If alternator fails to supply rated output, stator windings may be shorted. If readings are not normal, replace stator.

BRUSHES

Visually check brushes for burn spots or discoloration caused by arcing. Check brush length and replace if less than .15" (3.8 mm). New brush protrusion should be .39" (9.8 mm). Check brush continuity by touching one lead of ohmmeter to brush and other ohmmeter lead to brush terminal in brush holder. Check both brushes in this manner. If continuity exists in both brushes, brushes and holder are okay. If continuity does not exist in either position, replace brush holder and regulator as an assembly.

RECTIFIER

1. Using an ohmmeter, clip one ohmmeter lead to negative diode heat sink. Touch other ohmmeter lead to each negative diode pin. Reverse ohmmeter leads and repeat test. Diodes should show continuity in one direction only. If continuity exists in one direction only, go to next step. If continuity exists in both directions or continuity does not exist in either direction, replace rectifier assembly.
2. Clip one ohmmeter lead to positive diode heat sink. Touch other ohmmeter lead to each positive diode pin. Reverse ohmmeter leads and repeat test. Diodes should show continuity in one direction only. If continuity exists in one direction only, diodes are okay. If continuity exists in both directions or continuity does not exist in either direction, replace rectifier assembly.

OVERHAUL

Note. For exploded view of alternator (Scheme 4)

Scheme 4

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

See also:
• TROUBLE SHOOTING - BASIC PROCEDURES