No-Load Test

Disconnect battery-to-alternator terminal "B" wire. See Fig 1. Using an ammeter and voltmeter, connect negative ammeter lead to disconnected alternator terminal "B" wire end, and connect positive ammeter lead to alternator terminal "B".
Connect voltmeter positive lead to alternator terminal "B" 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 REGULATED OUTPUT SPECIFICATIONS table.

ALTERNATOR REGULATED OUTPUT SPECIFICATIONS ⁽¹⁾

Application

Amps

⁽²⁾ Volts

Cressida

14.0-15.0

Except Cressida & Land Cruiser

13.9-15.1

Land Cruiser

13.8-14.4

⁽¹⁾	Specification given is with engine speed at 2000 RPM.

⁽²⁾	Correct reading 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. See Fig 2. If voltage climbs above specified range, replace IC regulator. If voltage remains below specified range, repair or replace alternator.

Fig 1: Testing Charging Circuit

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Fig 2: Alternator Full Field Output Test (Camry, Celica, Cressida & Supra)

Fig 3: Test Alternator Full Field Output (Corolla, MR2, Paseo & Tercel)

Fig 4: Testing Alternator Full Field Output (Land Cruiser)

Fig 5: Alternator Full Field Output Test (Pickup, Previa & 4Runner)