Diode Test; Dual Circuit Alternator; Alternator Output Test - Briggs & Stratton Twin Cylinder L-Head Repair Manual

RED TEST
CLIP TO
OUTPUT PIN
TERMINAL
THE BATTERY MUST BE IN GOOD
CONDITION FOR THIS TEST
Fig. 14 – Testing DC Output

Diode Test

In the Diode Test position, the meter will display the
forward voltage drop across the diode(s). If the voltage
drop is less than 0.7 volts, the meter will "Beep" once
as well as display the voltage drop. A continuous tone
indicates continuity (shorted diode) An incomplete
circuit (open diode) will be displayed as "OL."
1. Insert RED test lead into
meter.
2. Insert BLACK test lead into COM receptacle in
meter.
3. Rotate selector to
4. Attach RED test lead clip to point "A" and Black test
lead clip to point "B," Fig. 15. (It may be necessary
to pierce wire with a pin as shown.)
a. If meter "Beeps" once, diode is OK.
b. If meter makes a continuous tone, diode is
defective (shorted). Replace.
c. If meter displays "OL," proceed to step 5.
5. Reverse test leads.
a. If meter "Beeps" once, diode is installed back-
wards.
b. If meter still displays "OL," diode is defective
(open). Replace.
6. If diode tests OK, check stator for bare wires or
other obvious defects. If grounded leads are not
visible, replace the stator.
"A"
BLACK LEAD
Fig. 15 – Testing Diode
BLACK TEST CLIP
TO POSITIVE
BATTERY
TERMINAL
receptacle in
(Diode Test) position.
RED
LEAD
"B"
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NOTE: Service replacement diode harnesses
are available. Use Rosin Core solder when
installing new harness. Use shrink tubing
or tape all connections. DO NOT USE
CRIMP CONNECTORS.

DUAL CIRCUIT ALTERNATOR

Dual circuit alternators use a single polarized plug with
two pins. One pin is for charging the battery and the
second is for the AC light circuit.
The dual circuit alternator provides DC current for
battery charging and an independent AC circuit for
headlights. The battery is not used for lights, so lights
are available even if the battery is disconnected or
removed.
Current for lights is available as long as the engine is
running. The output depends upon engine speed, so
brightness of the lights changes with engine speed. 12
volt lights with a total rating of 60 to 100 watts may be
used. With lights rated at 70 watts, the voltage rises
from 8 volts at 2400 RPM to 14 volts at 3600 RPM.
The current from the DC side of the alternator is
unregulated and is rated at 3 amps. The output rises
from 2 amps at 2400 RPM to 3 amps at 3600 RPM.
WHEN CHECKING THE
PONENTS, MAKE THE TESTS IN THE FOLLOWING
SEQUENCE:

Alternator Output Test

1. Insert RED test lead into 10 A receptacle in meter.
2. Insert BLACK test lead into COM receptacle in
meter.
3. Rotate selector to
4. Attach RED test lead clip to DC output pin in
connector, Fig. 16.
5. Attach BLACK test lead clip to positive (+)
battery terminal.
RED TEST
LEAD TO DC
OUTPUT PIN
THE BATTERY MUST BE IN GOOD
CONDITION FOR THIS TEST
RED
WIRE
RAISED RIB ON
DC
CONNECTOR INDICATES
OUTPUT
DC OUTPUT PIN SIDE
PIN
Fig. 16 – Testing DC Output
ALTERNATOR COM-
(DC amps) position.
BLACK LEAD
TO POSITIVE
BATTERY
TERMINAL
AC
OUTPUT
PIN
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