Current Output Test - Mercury MerCruiser D2.8L D-Tronic Service Manual

CHARGING SYSTEM

Current Output Test

Perform this test to check if alternator is capable of producing rated current output, using
a 0-80 amp DC ammeter.
Ensure engine compartment is well-ventilated and that there are no gasoline vapors
present (during the test) to prevent the possibility of an explosion and/or a fire,
should a spark occur.
1. Disconnect negative (–) battery cable from battery.
2. Disconnect BLUE 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. Turn on all accessories and turn ignition switch to RUN position, and allow glow plug
system to operate through one cycle. Turn switch to OFF position. Turn off accessories.
5. Start engine and adjust engine speed to 1500-2000 rpm. Quickly observe ammeter.
Reading should be at least 30 amps.
6. If reading is low, stop engine and connect a jumper wire between alternator output
terminal and regulator terminal. Repeat Steps 4. and 5.
7. If reading is now within specifications, diodes are faulty. Replace the alternator.
8. If reading is still low with jumper wire connected, perform Voltage Output Test, following.
Page 4B-14
a - Output Wire - BLUE
b - Ammeter (0-80 Amps)
c - Jumper Lead
d - Regulator Terminal
e - Ground
WARNING
a
e
c
d
SERVICE MANUAL NUMBER 22
b
72787
90-860074--1 FEBRUARY 2002