CHARGING SYSTEM
SERVICE MANUAL NUMBER 24
Circuitry
Perform the following tests, using a 0-20 volt DC voltmeter, to check that all of the circuits
between the alternator and the other components within the alternator system are in good
condition.
OUTPUT CIRCUIT
1.
2.
3.
Ensure battery is fully charged by using the hydrometer test outlined in 4A.
Start engine and increase RPM to approximately 1500 rpm.
Check voltage reading. The voltage should read between 13.8 and 14.2 volts. If the
reading is below 13.8 volts:
a. Connect positive (+) voltmeter lead to alternator output post.
b. Connect negative (–) lead to ground post on alternator.
c. Wiggle engine wiring harness while observing voltmeter. Meter should indicate ap-
proximate battery voltage and should not vary. If no reading is obtained, or if reading
varies, go to “Resistance” in this section.
d
a
e
c
72784
b
Typical
a - Output Wire - ORANGE
b - Excitation Wire - PURPLE
c - Sensing Wire - RED/PURPLE
d - Voltmeter (0-20 Volts)
e - Ground
EXCITATION CIRCUIT
1.
2.
3.
Connect positive (+) voltmeter lead to tie strap terminal on alternator and negative (–)
lead to a ground terminal on alternator (Test 1).
Turn ignition switch to ON position and note voltmeter reading. Reading should be 1.3
to 2.5 volts.
If no reading is obtained, an opening exists in alternator excitation lead or in excitation
circuit of regulator. Unplug PURPLE lead from regulator. Connect positive voltmeter
lead to PURPLE lead and negative voltmeter leads to ground (Test 2). If voltmeter now
indicates approximate battery voltage, voltage regulator is defective and must be
replaced. If no voltage is indicated, check excitation circuit for loose or dirty connections
or damaged wiring.
Page 4C-10
90-861327--1 OCTOBER 1999
| Categories | Mercury MerCruiser Manuals |
|---|---|
| Tags | Mercury MerCruiser 305 CID, Mercury MerCruiser 350 CID |
| Model Year | 1998, 1999, 2000, 2001 |
| Download File |
|
| Document File Type | |
| Copyright | Attribution Non-commercial |
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