Connect charging system test equipment as described in manufacturer's instructions. Check charging system output voltage at 2000 RPM. If output voltage is high, replace voltage regulator and retest. If output voltage is low, go to next step. If output voltage is correct, go to step 3). See GENERATOR OUTPUT SPECIFICATIONS table.
If output voltage is low, by-pass regulator (full field generator) by grounding terminal "F" at back of generator. See Fig 1. Recheck charging system output voltage. If voltage now exceeds output voltage specified in GENERATOR OUTPUT SPECIFICATIONS table, replace regulator and recheck. If output voltage is still incorrect, repair or replace generator.
With engine at 2000 RPM, place the heater blower switch on highest setting and turn on headlights (high beam). Ammeter reading should be 30 amps or more. If amperage output is incorrect, repair or replace generator.

GENERATOR OUTPUT SPECIFICATIONS ⁽¹⁾

Application

Amps

Volts

LS400

10 Or Less

13.7-14.8

⁽¹⁾	Measured at 77°F (25°C) and 2000 RPM.

Fig 1: Full Fielding Generator

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

Generator Output