Testing - On- Vehicle; Battery Discharge Through Alternator; Overcharged Battery - Jeep 1987 Wrangler Workshop Manual

ELECTRICAL
CHARGING SYSTEM - DELCO
Battery Discharge Through Alternator
If the alternator is suspected of discharging
the battery because of e x c e s s i v e current
leakage, perform the following test procedure
with a No. 158 bulb and bulb socket with
attached jumper wires.
WARNING: Failure to disconnect the battery
negative cable before disconnecting the
alternator output wire may result in injury.
Disconnect the battery negative cable.
Disconnect the output wire (red) from the
alternator output terminal. Prevent this wire from
touching any metal.
Connect the test bulb jumper wires in series with
the output wire and the alternator output
terminal.
Connect the battery negative cable. The bulb
should NOT light. If the bulb lights, even dimly,
replace the alternator bridge rectifier.
Disconnect the battery negative cable and
remove the jumper wires.
Disconnect the wires from No. 1 and No. 2
terminals of the alternator.
Connect the test bulb jumper wires between the
No. 1 terminal at the alternator and the battery
positive post.
Connect the battery negative cable. The bulb
should NOT light. If the bulb lights, even dimly,
test the alternator diode trio.
If the diode trio is NOT defective, replace the
voltage regulator.
Connect the test bulb jumper wires between the
No. 2 terminal at the alternator and the battery
positive post. The bulb should NOT light. If the
bulb lights, even dimly, replace the voltage
regulator.
Overcharged Battery
To determine battery condition, refer to the
Battery Section.
If an obvious overcharge condition exists, as
evidence by excessive spewing of electrolyte,
replace the voltage regulator.
TESTING — ON - V E H I C L E
Perform visual inspection as outined.
With the ignition switch ON and all wiring
harness leads connected, connect a voltmeter
from:
• alternator " B A T " terminal-to-ground (1),
12.5V
• alternator No. 1 terminal-to-ground (2), 2-4V
• alternator No. 2 terminal-to-ground (3), 12.5V
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