Midtronics EXP-802, Instruction Manual

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Midtronics Inc. 7000 Monroe Street Willowbrook, IL 60527 www.midtronics.com
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EXP-803 Chapter 4: System Test
7. TURN HIGH BEAMS AND BLOWER MOTOR ON, IDLE EN-
GINE: After a few seconds, the analyzer will ask you to turn
on the accessory loads. It will determine if the charging
system is able to provide enough current for the demands
of the electrical system.
IMPORTANT: Turn on the high-beam headlights
and the blower to high. Do not use cyclical loads
such as air conditioning or windshield wipers.
8. TESTING ALTERNATOR AT IDLE, LOADS ON: The analyzer
will determine if the charging system is able to provide
sufficient current for the demands of the vehicle’s electri-
cal system.
9. REV ENGINE WITH LOADS ON FOR 5 SECONDS: The ana-
lyzer will test the charging system with the loads on and
prompt you to rev the engine. Gradually increase the rev
until the analyzer tells you to HOLD the rev level as the bar
on the display moves to the right.
10. ACQUIRING DATA....HOLD ENGINE RPM: Continue to hold
the RPM while the analyzer takes system measurements.
11. ENGINE REV DETECTED, IDLE ENGINE: The analyzer has de-
tected the rev. Press NEXT to continue.
12. ANALYZING CHARGING SYSTEM DATA: The analyzer is
completing its final analysis of the charging system data.
13. TURN OFF LOADS AND ENGINE: Press NEXT to display the
results. See Table 5 on the next page for an explanation for
the test decisions.
NOTE: When the option TRACK CALLS is enabled,
the tester writes the results to the data card.
Charging System Test Results
Alternator
decision Loads-off
DC voltage
at rev
Loads-on
DC voltage
at rev
Normal DC
voltage
range
Bar graph
showing
DC voltage
within
normal
range with
loads on and
off
Graph
of diode
waveform
Peak-to-
peak AC
voltage
Charging System Decisions
Decision Action
NO
PROBLEMS
The system is showing normal output from
the alternator. No problem detected.
NO OUTPUT The alternator is not providing charging
current to the battery.
LOW OUTPUT The alternator is not providing enough
current to power the system’s electrical
loads and charge the battery.
HIGH OUTPUT The voltage output from the alternator to
the battery exceeds the normal limits of a
functioning regulator.
The regulator controls voltage output
based on the battery voltage, under-hood
temperature, and vehicle loads used.
In other words, it controls the maximum
voltage the system can produce based on
the current needs and amount of current
that can be produced by the spinning of
the rotor in the alternator. The normal high
limit of a typical automotive regulator is
14.5 volts +/–0.5. Refer to the manufacturer
specifications for the correct limit, which
may vary by vehicle type.
A high charging rate will overcharge the
battery and may decrease its life and
cause it to fail. If the battery test decision
is REPLACE and the charging system
test shows a HIGH OUTPUT, check the
battery’s electrolyte levels. A symptom
of overcharging is battery fluid spewing
through the vent caps, which causes low
electrolyte levels and will harm the battery.
Diode Decisions
Decision Action
EXCESSIVE
RIPPLE
One or more diodes in the alternator are
not functioning or there is stator damage,
which is shown by an excessive amount of
AC ripple current supplied to the battery.
OPEN PHASE The analyzer has detected open or
shorted diode, or an open phase within the
alternator. Replace the alternator.
OPEN DIODE
SHORTED
DIODE