Alternator Output Test; Diode Test; Charging Circuit (Red Wire); Lighting Circuit (White Wire) - Briggs & Stratton Twin Cylinder L-Head Repair Manual

WHEN CHECKING THE
PONENTS, MAKE THE TESTS IN THE FOLLOWING
SEQUENCE:

Alternator Output Test

1. Insert RED test lead into
meter.
2. Insert BLACK test lead into COM receptacle in
meter.
3. Rotate selector to V~ (AC volts) position.
4. Attach RED test lead clip to output terminal,
Fig. 19.
5. Attach BLACK test lead clip to engine ground.
RED TEST CLIP
TO AC OUTPUT
PIN
BLACK TEST LEAD
TO A GOOD GROUND
SURFACE
Fig. 19 – Testing Alternator Output
6. With engine running at 3600 RPM, output should
be no less than 28 Volts AC.
7. If no output or low output is found, replace stator.
8. If alternator output is good, test diodes located in
wiring harness.

Diode Test

NOTE: One diode is for the charging circuit and
the other diode is for the lighting circuit.
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."

Charging Circuit (Red Wire)

1. Insert RED test lead into
meter.
2. Insert BLACK test lead into COM receptacle in
meter.
3. Rotate selector to
4. Attach BLACK test lead clip to point "A," Fig. 20. (It
may be necessary to pierce wire with a pin as
shown.)
5. Insert RED test lead probe into harness connector.
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 6.
ALTERNATOR COM-
receptacle in
receptacle in
(Diode Test) position.
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6. Reverse test leads.
a. If meter "Beeps" once, diode is installed back-
wards.
b. If meter still displays "OL," diode is defective
(open).
RED
LEAD
Fig. 20 – Diode Testing – Charging Circuit

Lighting Circuit (White Wire)

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," Fig. 21. (It
may be necessary to pierce wire with a pin as
shown.)
5. Insert BLACK test lead probe into harness con-
nector.
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 6.
6. Reverse test leads.
a. If meter "Beeps" once, diode is installed back-
wards.
b. If meter still displays "OL," diode is defective
(open).
BLACK
RED
LEAD
LEAD
Fig. 21 – Diode Testing – Lighting Circuit
BLACK
LEAD
RED
WIRE
"A"
receptacle in
(Diode Test) position.
WHITE
WIRE
"A"
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