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No-Load Test

  1. Disconnect battery-to-generator terminal "B" wire. See Fig 1. Using an ammeter and voltmeter, connect negative ammeter lead to disconnected generator terminal "B" wire end, and connect positive ammeter lead to generator terminal "B".
  2. Connect voltmeter positive lead to generator 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 GENERATOR REGULATED OUTPUT SPECIFICATIONS  table. If voltage is more than specified, replace IC regulator. If voltage is less than specified, go to next step.
  3. Locate small hole in back of generator. See Fig 2. It may be necessary to remove generator end cover to access hole. Using a probe, ground generator terminal "F" (full field) to generator case. See Fig 2. If voltage is more than specified range, replace IC regulator. If voltage is less than specified range, repair or replace generator.
GENERATOR REGULATED OUTPUT SPECIFICATIONS (1)

Application Amps Volts
Avalon 10 Or Less 13.2-14.8
Camry, Camry Solara & Corolla 10 Or Less 13.5-15.1
Celica & RAV4
With Temperature At 77°F (25°C) 10 Or Less 14.0-15.1
With Temperature At 239°F (115°C) 10 Or Less 13.5-14.3
Land Cruiser & Sienna 10 Or Less 13.2-14.8
Tacoma
With Temperature At 77°F (25°C) 10 Or Less 13.7-14.7
With Temperature At 239°F (115°C) 10 Or Less 13.2-14.0
Tundra
V6 10 Or Less 13.2-14.8
V8
With Temperature At 77°F (25°C) 10 Or Less 13.7-14.7
With Temperature At 239°F (115°C) 10 Or Less 13.2-14.0
4Runner
With Temperature At 77°F (25°C) 10 Or Less 13.7-14.7
With Temperature At 239°F (115°C) 10 Or Less 13.2-14.0
(1) Specification given is with engine speed at 2000 RPM.
Fig 1: Testing Charging Circuit
G96I06124Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Fig 2: Testing Generator Full Field Output (Typical)
G96C06121Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002