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24
FUEL INJECTOR MODE
1
2
3
4
• Select INJECTOR from the Menu.
• Back-probe on the negative side of the in-
jector either at the injector or at the PCM.
• These four data points represent the cor-
responding waveform points.
• When the engine is running (or cranking)
the tool’s red and green indicator LEDs
will blink to indicate a good signal from
the ECM/PCM.
• The main screen will display complete in-
jector circuit data for quick comprehensive
injector circuit diagnoses.
ON-
1
ms
= Injector Pulse On Time (milliseconds) -
This is the total
amount of time that the fuel injector is energized and supplying fuel to the
cylinder. This can be compared to scan tool PID data to see if commanded
on-time equals actual on-time.
= Inductive Kick Voltage -
Normal inductive kicks range
between 55 and 90 volts. You should see a similar voltage number from
each of the injectors on the engine. NOTE: The height of the inductive kick
is sometimes cut-off by an internal ECM diode to about 35-45 volts. This
test does not apply to hi-pressure injectors used on diesel engines and
gasoline direct-injection engines.
ECM Ground Voltage -
The engine computer activates
each fuel injector by completing the ground circuit with an internal transis-
tor switch. When the fuel injector is energized, the ECM ground voltage
should be closed to zero volts. Actual measured ECM ground voltage can
vary, and may be closer to 0.5 volts because of the internet resistance of
the switching transistor.
=
Injector Supply Voltage -
This is the battery power being
supplied through the fuel injector itself. Measured voltage should be close
to fully battery voltage. There may be small voltage drops in the circuit,
however, anything more than 0.5 volt loss from the source battery voltage
should be investigated.
IND-K V
2
ECM
V =
3
INJ V
4
