7. With accessories in the off position, no radio, or
lights etc. View and record the results from the display.
8. Open throttle, keep engine speed between 1500
and 2500 RPM. Have an assistance help hold
speed so you can view and record the results from
the display.
9. Fully load the electrical system by turning on the
lights, windshield wipers, and the blower fan on high.
10. Turn off all accessories, return engine to idle
and shut off. Refer to vehicle service manual for
recommended voltage outputs. If voltage readings
were as expected, then charging system is normal.
Typical charging system output voltages:
At normal idle, display should read 13.2 to 15.2 volts.
With idle speed increased, voltage reading should
not change by more than 0.5 volt.
With idle speed increased under load, voltage
should not drop under 13 volts.
If any of the above results were less than the
vehicles specifications check the following.
Check for corroded battery terminals, a loose belt,
bad voltage regulator, alternator, or poor terminal
connections.
Throttle Position/EGR Valve Sensors
Throttle Position/EGR Position Sensors are
potentiometers or a variable resistor. The ECU uses
the information provided by the sensors to
determine the position and direction of movement.
The following are applications for a position sensor;
Throttle, EGR valve, and Vane air flow.
1. Insert BLACK test lead into COM test lead jack.
2. Insert RED test lead into test lead jack.
3. Disconnect wiring harness from sensor. Refer to
vehicle service manual for your vehicles pin
identifications. You’ll be looking for the power,
ground, and signal pin locations. Typically you’ll find
the signal pin in the center of the three pins. If you
have four pins your sensor incorporates an idle
Battery Current Draw
Test to determine the amount of current being drawn
from the battery with the ignition key off. This test
helps to identify possible sources of a short or
excessive battery current draw. Excessive draw
could lead to shortened battery life, or a dead battery.
1. Ignition OFF including all accessories. Be sure
trunk, hood, and dome lights are all OFF.
2. Insert BLACK test lead into COM test lead jack.
3. Insert RED test lead into the “A” (or mA) test
lead jack.
4. Disconnect positive (+) red battery cable.
5. Add the alligator clips and connect RED clip to
positive (+) battery terminal/post of the battery.
6. Connect BLACK test lead to positive (+) red
battery cable (that as disconnected).
DO NOT start vehicle during this test, doing so will
damage the meter, and void warranty.
7. Turn meters range selector to 10A DC (or 200
mA) position.
8. View results on display, typical current draw is 0.1
ampere (100mA). Refer to vehicle service manual
for your vehicles specific Engine off Battery Current
Draw. Vehicle clocks, ECU’s and presets are
calculated in the normal 100mA draw.
Finding Excessive Current Draw
Display reading in the steps above are well outside
manufacturer’s specifications.
1.While watching the meter display remove fuses
from the fuse box one at a time until source of
excessive current draw is located. When the
suspect fuse is pulled there should be a drop in the
amps displayed on the meter. For non-fused circuits
such as headlights, relays, and solenoids it may
involve unplugging the unit from the wiring harness.
When the source of excessive current drain is found
service as needed.
Charging System Voltage
Check the charging system for output voltage.
Charging system provides power to maintain the
battery and feed power to the rest of the vehicles
electrical systems (lights, fan, radio etc).
1. Insert BLACK test lead into COM
2. Insert RED test lead into test lead jack.
3. Add the alligator clips and connect RED clip to
positive (+) terminal/post of battery.
4. Connect BLACK clip to negative (-) terminal
of battery.
5. Turn meters range selector to 20V DC range.
6. Be sure the meter and connecting wire are clear
from all moving parts. Start engine and let it idle.
BATTERY/STARTING/CHARGING CONT.
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ENGINE SENSORS TESTS
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+5V in
Signal Out
Ground
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