Alternator Replacement Determination - Borg Warner Delco Remy 28MT Diagnostic Procedures Manual

3-28. TEST COMPLETION.
For 12-volt systems, proceed with Alternator Replacement
Determination. For 24-volt systems, proceed as follows:
1. Reconnect temporary 12-volt system back to 24-volt system.
2. If Magnetic Switch Circuit Test was delayed, conduct at this
time.
3. After completing Magnetic Switch Circuit Test, be sure to
reconnect lead to S starter solenoid terminal. Then proceed with

Alternator Replacement Determination.

NEGATIVE
CIRCUIT LOSS
(25)
FIGURE 3-8. Alternator Wiring Test -
Typical 12-Volt System
3-29. ALTERNATOR REPLACEMENT
DETERMINATION
If the alternator wiring circuits are okay, conduct the following
tests to determine if the alternator must be replaced.
Make sure that alternator mounting hardware is secure and that
belts are OK before testing alternator.
Batteries must be satisfactorily load tested and near full charge
with more than 12.4 volts — no load voltage.
delcoremy.com
Remove carbon pile and voltmeter.
CARBON
PILE
POSITIVE
CIRCUIT
LOSS (24)
NOTE
NOTE
3-30. ALTERNATOR VOLTAGE OUTPUT TEST.
shop temperature (See Figure 3-9).
Connect
1. Digital voltmeter from positive alternator terminal to alternator
ground.
Test
1. Start engine and make sure all vehicle electrical loads are
turned off. Fast idle engine until voltage stabilizes (does not
increase) for two minutes.
2. Check that alternator output voltage does not exceed 15.5
volts (31 volts for 24-volt system). Remove voltmeter.
NEGATIVE
CIRCUIT LOSS
(25)
DP-1026
FIGURE 3-8. Alternator Wiring Test -
3-31. ALTERNATOR AMPERAGE OUTPUT TEST.
test at shop temperature (See Figure 3-10).
Connect
1. Carbon pile across the vehicle batteries hooked in parallel.
2. Induction ammeter clamped around alternator output wire.
CARBON
PILE
POSITIVE
CIRCUIT
LOSS (24)
Typical 12-Volt System
Conduct this test at
DP-1026
Conduct this
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