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8.14
Section 8
Electrical System and Components
Figure 8-16. “Pass” Indicator.
**The tester is powered by a 9-volt battery. Most
SAMs are designed to operate down to a minimum
of 7.25 volts. If the tester battery drops below that
level, incorrect test readings will result. The tester
battery should be checked periodically by
connecting a DC voltmeter between the red and
green lead wires, with the tester connected to a
SAM. Press and hold the test button for a full test
cycle (‘‘F’’ or ‘‘P’’ appears and then display shuts
off), while monitoring the voltage reading on the
voltmeter. If the voltage drops below 7.5 at any time
during the cycle, the 9-volt tester battery must be
replaced. Use an extended life (alkaline) battery.
To replace the battery, remove the outer set of screws
on the faceplate and carefully lift the panel from the
body. Unplug the connector and pull battery (with
mounting tape) off the back of the tester. Attach the
connector to the new battery and mount the battery to
the case with double-backed tape. Reinstall the
faceplate and secure with the four screws.
Battery Charging System
General
Most engines are equipped with a 15 or 20 amp
regulated charging system. Some have a 25 amp
regulated charging system. See Figure 8-17 and 8-18
for the 15/20/25 amp charging system diagram. Some
engines utilize a 3 amp unregulated system with
optional 70 watt lighting circuit. Refer to Figure 8-23.
NOTE: Observe the following guidelines to avoid
damage to the electrical system and
components:
• Make sure the battery polarity is correct. A
negative (-) ground system is used.
• Disconnect the rectifier-regulator plug and/or the
wiring harness plug before doing any electric
welding on the equipment powered by the
engine. Also, disconnect all other electrical
accessories in common ground with the engine.
• Prevent the stator (AC) leads from touching or
shorting while the engine is running. This could
damage the stator.
Figure 8-15. Select Test Number.
4. If you get a “-“ sign instead of the numerical
sequence, and/or an “F” at the end of the test
cycle, recheck all of the connections, check the
condition of the tester battery** and repeat the
test. If you get the “-“or “F” sign again in the
retest replace the SAM.
*IMPORTANT!
Allow 15-20 seconds for the tester to clear and reset
itself between tests or if the test is interrupted before
completion of the test cycle. Otherwise, a false reading
may be displayed in the form of a “-” or a faint “8”.