No-Load Test

Disconnect alternator "B" terminal wire. Using an ammeter and voltmeter, connect negative ammeter lead to disconnected alternator terminal "B" wire and positive lead to alternator "B" terminal.
Connect voltmeter positive lead to alternator "B" terminal and negative lead to ground. See Fig 1.

Start engine and increase engine speed to 2000 RPM. Both meters should read within specification. See ALTERNATOR OUTPUT SPECIFICATIONS table.

ALTERNATOR OUTPUT SPECIFICATIONS @ 2000 RPM

Application

Amps

⁽¹⁾ Volts

MR2/Previa

13.9-15.1

⁽¹⁾	With temperature at 77°F (25°C).

If voltage is more than specified, replace IC regulator. If voltage is less than specified, ground "F" (full field) terminal. If voltage now climbs above specified range, replace IC regulator. If voltage remains below specified range, repair or replace alternator.

Fig 1: Testing Charging Circuit