Bosch MMD 540H Mode D'emploi page 13

22 | MMD 540H Hybrid Multimeter | Meter Functions
Meter Functions – Duty Cycle (%)
f Select the "%DUTY"
Cycle function with the
rotary switch.
Insert:
f Black lead in COM
terminal.
f Red lead in V-Ω-RPM
terminal.
Connect the Black test
probe to ground.
Connect the Red test probe
to the signal wire circuit.
The illustration for a mixture
control solenoid is shown
with the metering rod in the
closed position. The meter
will display the percentage
of time the plunger is in the
closed position. (low duty
cycle) during one duty cycle.
Robert Bosch LLC MMD 540H Instruction Manual | Version 1 | December 2010
Black– Red+
Mixture
Control
Shown
MMD 540H Hybrid Multimeter | Meter Functions | 23
Meter Functions – ms-PULSE (Pulse Width)
& ms-PERIOD (Period)
Pulse Width is the length of time an actuator is energized. For
example, fuel injectors are activated by an electronic pulse from the
Engine Control Module (ECM).
This pulse generates a magnetic field that pulls the injectors 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.
Measuring Pulse Width on Port Fuel injectors is described on the
following page.
(continued on next page)
MMD 540H Instruction Manual | Version 1 | December 2010 Robert Bosch LLC