Service Manual

Keep these points in mind when testing or servicing the
flywheel alternator:
1.
Be sure engine is being run long enough and fast
enough to recharge battery after each start. Charging
system tests require a full charged battery. Alternator
output is reduced in direct proportion to engine rpm.
Also, power required for accessories reduces power
available to recharge battery.
2. The regulator-rectifier has built in protection against
open circuits or short circuits on the alternator
output
(B+) terminal. Either condition will cause the
regulator-rectifier to shut off and appear as
if it is not
functioning. Priortochecking the regulator-rectifier,
check all wiring between the regulator-rectifier
B+
terminal and the battery positive (+) terminal to
assure it is free of open circuits, resistances or short
circuits. Also,
if the battery is extremely discharged
it may have insufficient power to “turn on” the
regulator-rectifier.
3. Be sure regulator-rectifier plug (connector) is in-
serted properly. Plug must bottom in receptacle; this
eliminates any resistance due to a poor connection.
Keep clean and tight.
4. Make sure alternator stator leads are not shorted
together.
5. Be sure regulator-rectifier has a good ground
connection. Mating surface for mounting must be
clean and fasteners tightened properly.
6. Never reverse the battery leads.
When the engine is running between
1800 to 2600 rpm,
observe the panel ammeter (if not already equipped,
connect a test ammeter).
If no charging is evident,
proceed with the
Alternator Output Test.
ALTERNATOR OUTPUT TEST
Use a volt-ohmmeter, such as the Simpson 270, when
testing the charging system.
1. Check battery voltage with unit not running. If not
within specifications (Table
1) charge battery before
proceeding
to step 2.
2. With the engine running, check the battery terminal
voltage (regulator output) using a DC voltmeter.
Voltage output should be within the values specified
in Table 1. If voltage is greater than specified,
replace regulator-rectifier assembly.
If voltage is
less than specified, proceed to step
3.
3.
Examine all wires for loose, corroded, broken con-
nections, short circuits, etc. Check fuses. Repair as
needed to assure complete circuits from regulator-
rectifier
B+ terminal to battery positive (+) terminal
and from battery negative
(-) terminal to regulator-
rectifier case.
If battery voltage remains low with
engine running, proceed to step
4.
4. Disconnect plug from regulator-rectifier and test
the AC voltage at the plug with engine running.
If AC
voltage reads more or less than specified in Table 1,
proceed to step
5. If AC voltage is as specified but
DC voltage is low, replace regulator-rectifier.
5. Use the Rx1 scale on the ohmmeter for detecting an
open or ground in the stator (unit not running).
Disconnect plug from the regulator-rectifier. Con-
nect one ohmmeter test lead to a stator wire,
connect the other test lead to ground. Reading
should show an open (no continuity).
If it doesn’ t,
stator must be replaced. If reading shows no con-
tinuity connect one ohmmeter lead to each wire
coming from the stator. Refer to Table
1 for resist-
ance specifications.
If resistance is not as specified,
replace stator.
If stator resistance readings are as
specified and windings are not shorted or open, low
AC voltage may
be due to loss of magnetism. If so,
blower wheel assembly must be replaced.