DESCRIPTION
Mitsubishi alternators are conventional 3-phase, self-rectifying type units containing 6 diodes (3 positive and 3 negative). A case-mounted Integrated Circuit (IC) regulator is used on all models.
Scheme 1
Scheme 2
BELT TENSION
| Application | New Belt | Used Belt | |
|---|---|---|---|
| Festiva | |||
| A/C Belt | 120-160 (55-75) | 110-130 (50-60) | |
| Alt. Belt | 110-130 (50-60) | 110-130 (50-60) | |
| Tracer | |||
| All Belts | 110-130 (50-60) | 110-130 (50-60) | |
| (1) Tension in Lbs. (Kg) Using Strand Tension Gauge | |||
| (1) | Tension in Lbs. (Kg) Using Strand Tension Gauge |
BELT ADJUSTMENTS (1)
TESTING (ON-VEHICLE)
Note. Check alternator wire harness connections and drive belt tension. Battery must be fully charged prior to beginning test. Wait at least 30 seconds after starting engine before measuring voltage.
ALTERNATOR TEST
- Turn ignition switch to "OFF" position. Disconnect negative battery cable. Remove output lead from alternator terminal "B". (Scheme 1)and (Scheme 2). Install a 100-amp ammeter in series to "B" terminal and disconnected output lead. Install positive lead of ammeter to "B" terminal and negative lead to disconnected output wire.
- Install a digital voltmeter between alternator "B" terminal and battery positive terminal. Install positive lead wire of voltmeter to "B" terminal and negative lead wire to positive terminal. Reconnect negative battery cable.
- Start engine. Turn accessories on until ammeter indicates 20 amps. If voltmeter indicates.2 volts, system is okay. If voltage is greater than.2 volts, wiring is defective between alternator "B" terminal, fusible link and battery positive terminal.
ALTERNATOR OUTPUT TEST
- Turn ignition switch to "OFF" position. Disconnect negative battery cable. Disconnect alternator output wire from "B" terminal. Connect an ammeter between "B" terminal and disconnected output wire. Connect a voltmeter between "B" terminal and ground. Connect positive voltmeter lead wire to alternator "B" terminal and negative wire to ground. Install an engine tachometer (if necessary) and reinstall battery ground cable open.
- Ensure voltmeter indicates battery voltage. If voltmeter reads zero volts, an open circuit is present in wire between alternator "B" terminal and battery negative terminal. Check grounds and fusible link.
- Turn headlights on and start engine. Set headlights at high beam and heater switch on "HIGH". Quickly increase engine speed to 2500 RPM and check alternator output current and shown on ammeter. Ensure minimum output is within specification. See ALTERNATOR OUTPUT SPECIFICATION table.
| Application | Specification | |
|---|---|---|
| Alternator Rating | ||
| 60-Amp | 42 Amps | |
| 65-Amp | 45 Amps | |
| 75-Amp | 52 Amps | |
ALTERNATOR OUTPUT SPECIFICATIONS
REGULATED VOLTAGE TEST
- Turn ignition switch to "OFF" position. Disconnect negative battery cable. Install a digital voltmeter between alternator terminal "L" (or "F") and ground. Connect positive voltmeter lead to "L" (or "F") terminal of alternator. Connect negative voltmeter lead to ground.
- Disconnect alternator output wire from alternator "B" terminal. Install an ammeter in series between "B" terminal and disconnected output wire. Connect negative ammeter lead wire to disconnected output wire. Install a tachometer and reconnect negative battery cable.
- Turn ignition switch to "ON" position and ensure voltmeter indicates 2-5 volts. If zero volts are present, there is an open circuit in wire between alternator "L" (or "F") terminal and positive battery terminal, or fusible link is blown.
- Start engine. Ensure all lights and accessories are off. Operate engine at 2500 RPM and read voltmeter when alternator output current drops to 10 amps or less. Voltage regulator is okay if voltage output is to specification. See REGULATOR VOLTAGE SPECIFICATION table.
| Ambient Temperature | Voltage |
|---|---|
| 4°F (-20°C) | 14.4-15-6 |
| 68°F (20°C) | 14.2-15.2 |
| 140°F (60°C) | 13.8-15.1 |
| 176°F (80°C) | 13.6-15.0 |
REGULATOR VOLTAGE SPECIFICATION
DIODE ASSEMBLY
- Check each diode with ohmmeter in both directions. If diodes show large resistance in one direction and small resistance in other direction, diodes are normal.
- If diodes show small resistance in both directions, it is shorted. If large resistance is shown in both directions, diode is open. If any diodes are defective, replace rectifier assembly.
ROTOR
Check continuity across rotor slip rings. Reading should be 2.0-2.6 ohms. If there is no continuity, replace rotor. Check continuity between individual slip rings and rotor core/shaft. If there is continuity, rotor coil or slip ring is grounded. Replace rotor.
STATOR
Ensure no continuity exists between stator coil leads and stator core. Check continuity between leads of stator coil. If there is no continuity, replace stator.
BRUSHES
- Replace brushes if worn to limit line. Standard brush spring tension should be 12-16 oz. (340-453 g). Replace if less than 7 oz. (198 g) or if springs are corroded.
- To remove brushes from holder, unsolder pigtail from terminal. To replace, solder pigtail to terminal ensuring 1/4" of brush will be located in brush holder.
TROUBLE SHOOTING
Note. For trouble shooting, see TROUBLE SHOOTING - BASIC PROCEDURES article in the GENERAL TROUBLE SHOOTING section.
OVERHAUL
For disassembly & reassembly, refer to Fig. (Scheme 3) for an exploded view of the Mitsubishi alternator.
Scheme 3
See also:
• TROUBLE SHOOTING - BASIC PROCEDURES