DESCRIPTION
Hitachi alternators are conventional 3-phase, self-rectifying alternators. Three positive and 3 negative diodes are used to rectify current. Most models are equipped with Integrated Circuit (IC) voltage regulators, except Isuzu gasoline engine equipped models.
The IC voltage regulator consists of integrated circuits using transistors. These transistors control current flow to alternator rotor, thus maintaining alternator output voltage at a constant value.
On the charge indicator light circuit, a diode monitors alternating voltage at the stator. When monitored voltage and charging voltage are equal, the charge indicator light is turned off.
| Model | Hitachi No. | |
|---|---|---|
| Maxima | LR190-704 | |
| Pickup (Gasoline) | ||
| 2WD Standard | LR160-140B, LR150-197B & LR150-98B | |
| 2WD Heavy Duty | LR160-78, LR160-78B | |
| 4WD | LR150-194B, LR150-177 | |
| Pickup (Diesel) | LR150-403 | |
| Pulsar NX | LR160-121 | |
| Sentra (Gasoline) | LR160-121 | |
| Sentra (Diesel) | LR150-402, LR160-401 | |
| Stanza | LR160-104, LR170-14 | |
| 200SX (Non-Turbo) | LR160-104 | |
| 200SX (Turbo) | LR170-706 | |
| 300ZX (1) | LR170-701B | |
| (1) Nissan 300ZX Turbo uses Mitsubishi alternator. | ||
| (1) | Nissan 300ZX Turbo uses Mitsubishi alternator. |
ALTERNATOR APPLICATION
Exploded View of Typical Hitachi Alternator. Scheme 4
ALTERNATOR TESTING
- Ensure battery is fully charged prior to beginning test. Turn ignition on and check charge indicator light on instrument panel. If light comes on, go to step 3). If light is off, disconnect alternator connector and ground "L" wire.
- If light remains off, replace indicator bulb and retest. If light comes on, reconnect alternator and ground "F" terminal by using a wire. (Scheme 5) If light is off, repair alternator. If light is on, replace IC regulator. NOTE: On diesel engine equipped models, remove the vacuum pump to ground "F" terminal.
- Start and run engine at idle. If light is dim, flickers or remains on (bright), repair alternator. If light goes off, run engine at 1500 RPM and turn on headlights. If charge indicator light goes off, go to step 5).
- If charge indicator light is dim, idle engine and measure voltage between terminals "B" (positive) and "L" (negative). If less than.5 volt, alternator is okay. If more than.5 volt, repair alternator.
- Run engine at 1500 RPM and measure terminal "B" voltage. If more than 15.5 volts, replace IC regulator. If 13-15 volts, idle engine and check indicator light. If off, system is okay. If on, repair alternator.
Nissan Alternator Test. Scheme 5
DISASSEMBLY
- Remove vacuum pump (if equipped). Remove brush cover (if equipped). Remove through bolts. Separate front cover from rear cover by lightly tapping on front cover with plastic hammer. On some Nissan models, rear cover may be hard to remove as a ring is used to lock rear bearing. NOTE: To facilitate rear cover removal, heat center of rear cover using a 200-watt soldering iron.
- Place front cover and rotor assembly in protected vise with pulley nut up. Remove pulley nut, washer, pulley, fan and spacer(s). Press out rotor. Remove screws from front cover. Lift out bearing retainer and bearing.
- Remove rear cover or condenser (if used), nuts, and insulator(s). Lift stator, diode assembly, and brush assembly from rear cover. On diesel engine alternators, if oil seal is damaged, pry out oil seal from rear cover.
- Unsolder stator leads from diode assembly. Disconnect diode assembly from IC regulator by removing rivet and unsoldering end terminal. If IC regulator is being replaced, remove 2 bolts. DO NOT remove bolts if regulator is NOT being replaced.
Note. Melting of solder should be done as rapidly as possible to prevent damage to diodes and IC regulator.
Exploded View of Typical Hitachi Diesel Engine Alternator. Scheme 6
BENCH TESTING
Note. Also see GENERAL SERVICING in this section.
Rotor
Connect ohmmeter to rotor slip rings. If reading is 4-5 ohms, rotor continuity is satisfactory. If not, rotor is defective. Connect ohmmeter between one slip ring and rotor core. If continuity exists, replace rotor assembly.
Stator
Using ohmmeter, check continuity between stator core leads. If there is is no continuity between leads, replace stator. Connect ohmmeter between stator core and to each stator lead. If there is no continuity, stator is good. If continuity exists, stator is grounded and must be replaced.
Diodes
Using an ohmmeter, check continuity on all diodes in both directions. Current should flow in one direction only. If current flows in both directions, diode is shorted. If current does not flow in either direction, diode is open. If any diode is defective, replace entire diode assembly.
Brushes
- Inspect brushes for freedom of movement in holder. Clean brush holder if necessary. Check brushes for cracks and wear. Check brush springs for corrosion or damage.
- On all alternators, replace brush holder assembly if brush wear has reached limit line on brush.
- Test brush holder to ensure no continuity exists between holder and brush. On Nissan alternators, protrusion of NEW brushes must be .41-.45" (10-11 mm).
REASSEMBLY
- To reassemble, reverse disassembly procedure. On diesel engine alternators, install oil seal (if removed). Install IC regulator on brush holder and install bolts. Solder IC regulator terminal to diode assembly and install rivet.
- Solder stator leads to terminals of diode assembly. Install diode assembly, IC regulator and stator. On most alternators, push brushes into holder. Retain brushes in position by inserting a wire through hole in alternator.
- Install bearing, rotor, fan and pulley on front cover. Tighten pulley nut to 29-43 ft. lbs. (39-59 N.m). On some alternators, fit ring into groove of rear bearing. (Scheme 7)
- Assemble front and rear covers. Insert and tighten through bolts to 24-36 INCH lbs. (3-4 N.m). Remove brush retaining wire. On diesel engine alternators, install brush holder and cover (if equipped). Install vacuum pump. Tighten vacuum pump bolts to 24-36 INCH lbs. (3-4 N.m).
