Alternator Output

Connect charging system test equipment as described in manufacturer's instructions. Check charging system output voltage at 2000 RPM. If output voltage is correct, go to step 3). See ALTERNATOR OUTPUT SPECIFICATIONS @ 2000 RPM table.
If output voltage is incorrect, bypass regulator (full field alternator) by grounding terminal "F" at back of alternator. See Fig 1. Check charging system output voltage once more. If voltage now exceeds output voltage specified in ALTERNATOR OUTPUT SPECIFICATIONS @ 2000 RPM table, replace regulator and recheck. If output voltage is still incorrect, repair or replace alternator.
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 alternator.

ALTERNATOR OUTPUT SPECIFICATIONS @ 2000 RPM ⁽¹⁾

Application

Amps

Volts

ES250

13.9-15.1

LS400

14.0-15.0

⁽¹⁾	Measured at 77°F (25°C).

Fig 1: Full Fielding Alternator