Alternator Test; Alternator Test Results - Midtronics EXP-925 Instruction Manual

EXP-925

Alternator Test

1. The tester starts checking for alternator output.
NOTE: If necessary the analyzer will ask if you are
testing a diesel engine. It will resume testing after
you make your selection.
2. Depending on whether you are working with an inte-
grated Amp clamp, you will be either prompted to TURN
OFF LOADS AND ENGINE or asked to CHECK IF CLAMP
POINTS AWAY FROM THE NEGATIVE BATTERY POST.
In case of the former, turn off vehicle loads (blowers,
interior light, radio, etc.) and the engine. Press the NEXT
soft key to continue.
3. ANALYZING CHARGING SYSTEM DATA
4. TURN OFF LOADS AND ENGINE: Turn off vehicle loads
(blowers, interior light, radio, etc.) and idle the engine.
NEXT
Press the soft key to continue.
NOTE: If necessary the analyzer will ask if you are testing
a diesel engine. It will resume testing after you make
your selection.
5. REV ENGINE WITH LOADS OFF FOR 5 SECONDS: Rev the
engine with the loads off. Gradually increase the rpm un-
til the analyzer tells you to HOLD the rev level as the bar
on the display crosses the rpm target line.
6. ACQUIRING DATA....HOLD ENGINE RPM: Continue to hold
the rpm while the Tester takes system measurements.
7. ENGINE REV DETECTED, IDLE ENGINE: The Tester has de-
tected the rev. Press the
8. TESTING ALTERNATOR AT IDLE, LOADS OFF: The analyzer
will next test the engine at idle for comparison to other
readings, and then test the diode ripple. Excessive ripple
usually means one or more diodes have failed in the al-
ternator or there is stator damage.
9. TURN HIGH BEAMS AND BLOWER MOTOR ON, IDLE EN-
GINE: After a few seconds, the Tester will ask you to turn
on the accessory loads. It will determine if the charging
system is able to provide enough current for the de-
mands of the electrical system.
IMPORTANT: Turn on the high-beam headlights, the
blower to high and the rear defogger. Don't use cyclical
loads such as air conditioning or windshield wipers.
10. 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 elec-
trical system.
11. REV ENGINE WITH LOADS ON FOR 5 SECONDS: The Tes-
ter 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 crosses the rpm target line.
12. ACQUIRING DATA....HOLD ENGINE RPM: Continue to hold
the rpm while the Tester takes system measurements.
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NEXT
soft key to continue.
13. ENGINE REV DETECTED, IDLE ENGINE: The Tester has de-
tected the rev. Press the
14. ANALYZING CHARGING SYSTEM DATA: The Tester is com-
pleting its final analysis of the charging system data.
15. TURN OFF LOADS AND ENGINE: Press the
to display the results.

Alternator Test Results

Loads-off
DC voltage
at rev
Loads-off
current at
rev if amp
clamp is
used
Normal
DC
voltage
range
Peak-to-
peak AC
voltage
NO PROBLEMS
Alternator Result
19
Chapter 5: System Test
NEXT
soft key to continue.
NEXT
Midtronics B.V. Hoofdveste 6 - 8
soft key
Alternator
decision
Loads-on DC
voltage at rev
Loads-on cur-
rent at rev if
amp clamp is
used
Bar graph
showing DC
voltage within
normal range
with loads on
and off
Graph of
diode
waveform
Houten NL