New Holland LS140 Workshop Manual page 554

Alternator wiring connections test
1. Disconnect the battery negative cable.
2. Disconnect the B+ cable (Red/ Dark Blue) from
the alternator B+ post, 1, and Field Excitation
lead (Light Green/Blue), from the alternator L
post, 2.
3. Reconnect the battery and turn the key start
switch on. Do not start the engine. Connect a
voltmeter, 3, between each of the disconnected
leads, 4 and 5, and ground. Battery voltage
should be indicated at both of the leads (voltage
at the Field Excitation lead will be slightly less
than battery).
If battery voltage is not indicated at both leads, a
continuity fault exists which must be traced and
corrected.
4. Disconnect the battery and reconnect the
removed leads to the alternator. Reconnect the
battery.
Charging Current and Controlled Voltage Tests
1. Switch off all electrical components. Disconnect
the battery negative cable.
2. Disconnect the B+ terminal, 1, at the alternator.
Connect an ammeter, 2, between the removed
(Red/Dark Blue) wire, 4, and the B+ terminal of
the alternator.
3. Connect a voltmeter, 3, between the alternator
B+ terminal and ground.
4. Start and run the engine at 2000 RPM and
observe the voltmeter and ammeter readings.
The voltmeter should register in excess of battery
voltage at 2000 RPM. When the ammeter
reading falls below 10 amps the voltmeter
reading should stabilize at 13.4 - 14.4 volts.
If the voltmeter reading exceeds 14.4 volts, the
regulator is faulty and must be replaced. After
replacement, repeat the charging current and
controlled voltage tests.
If the voltmeter reading is below 13.4 volts, the
alternator is faulty or there is a high resistance
fault in the external portion of the charging
system.
If the ammeter registers zero amperes, a faulty
alternator is indicated. Turn off the engine and
conduct the "alternator component tests" as
detailed in this chapter.
SECTION 55 - ELECTRICAL SYSTEM
SM463-162
SM463-163
55-129
4
5
1
3
2
4
2
1
3
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