5.11 ms-PULSE (Pulse Width) & ms-
PERIOD (Period)
5.11.1 Pulse Width is the length of time an
actuator is energized. For example, fuel
injectors are activated by an electronic
pulse from the Engine C Control Module
(ECM). This pulse generates a magnetic
field that pulls the injector nozzle valve
open. The pulse ends and the injector
nozzle is closed. This open to close time
is the Pulse Width and is measured in
milliseconds( ms). The most common
automotive application for measuring
pulse width is on fuel injectors. You can
also measure the pulse width of the fuel
mixture control solenoid and the idle air
control motor.
This exercise shows how to measure
P u l s e W i dt h ( m S ) o n P o r t F u e l
injectors.
5.11.2 Select the “mS-Pulse” function with the
rotary switch .
5.11.3 Press the Trigger± button, the negative
(-)trigger slope is displayed on the display.
NOTE:
The applied time for most fuel injectors is
displayed on the negative (-) slope.
5.11.4 Insert the black lead into the COM
terminal.
5.11.5 Insert the red lead into the V-
Ω
-RPM
terminal.
5.11.6 Connect jumper wires between the fuel
injector and the harness connector.
5.11.7 Touch the Black test probe to a good
ground at the fuel injector or the negative
(-) vehicle battery post.
5.11.8 Touch the Red test probe to the fuel
injector solenoid driver input on the
jumper cable.
5.11.9 Start the engine. A pulse width in
milliseconds should be read.
Note: Initially, the unit will read “OL”, then
readings will descend and stabilize to the
actual pulse.width. If “OL” remains,
re-check yourconnections.
Fig.9
