Current Output Test - Mercury 305 CID Service Manual

5. If reading is between 6.0 and 7.0 volts, rotor field
circuit probably is open. Remove regulator and
inspect for worn brushes or dirty slip rings. Re-
place brushes if less than 1/4 in. (6 mm) long. If
brushes and slip rings are in good condition, dis-
assemble and perform rotor test as outlined un-
der "Component Testing - Rotor" following.
TEST 1
c
a - Excitation Wire - PURPLE
b - Sensing Wire - RED/PURPLE
c - Tie Bar
d - Voltmeter (0-20 Volts)
e - Ground
SENSING CIRCUIT
1. Unplug RED/PURPLE lead from voltage regula-
tor.
2. Connect positive (+) voltmeter lead to red/purple
lead and negative (–) voltmeter lead to ground
terminal.
Index
4C-6 - CHARGING SYSTEM
TEST 2
d
e
b
a
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3. Voltmeter should indicate battery voltage. If bat-
tery voltage is not present, check sensing circuit
(red/purple lead) for loose or dirty connection or
damaged wiring.
b
a - Output Wire - ORANGE
b - Excitation Wire - PURPLE
c - Sensing Wire - RED/PURPLE
d - Voltmeter (0-20 Volts)
e - Ground

Current Output Test

Perform this test to check if alternator is capable of
producing rated current output, using a 0-50 amp DC
ammeter.
! WARNING
Be sure that engine compartment is well-venti-
lated and that there are no gasoline vapors pres-
ent (during the test) to prevent the possibility of
an explosion and/or a fire, should a spark occur.
1. Disconnect negative (–) battery cable from bat-
tery.
2. Disconnect orange lead from alternator output
terminal and connect ammeter in series between
lead and output terminal. Connect positive (+)
side of ammeter toward output terminal.
3. Reconnect negative battery cable.
4. Remove coil wire from distributor cap tower and
ground it to block. Turn on all accessories and
crank engine over with starter motor for 15-20
seconds.
d
a
e
c
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