INTRODUCTION TO THE HMMWV - OD1615 - LESSON 4/TASK 1
cut directly in the rim of the flywheel itself.
The starter is mounted on
the flywheel housing.
The starter used on the HMMWV is a 24 volt unit activated by the RUN/START
switch through a solenoid mounted on the starter motor housing. The switch
is placed to the RUN position and the WAIT TO START lamp illuminates.
A
relay in the protective control box (PCB) energizes the glow plugs and after
approximately six seconds, the WAIT TO START lamp will extinguish.
The
vehicle may now be started by positioning the switch to the START position.
The starter will engage the crank and the engine.
Releasing the switch
allows it to return to the RUN position.
In other words, the switch is
spring-loaded to the RUN position. An ac output from the alternator to the
PCB prevents the starter from reengaging once the engine is running.
A
neutral (safety) switch mounted in the transmission quadrant prevents the
vehicle from being started in any gear other than neutral (N).
d. Wiring Design.
The vehicle wiring design uses a harness type
construction and a modular approach that separates the harness into four
major subassemblies. These subassemblies are engine, body, simplified test
equipment/internal combustion engine (STE/ICB), and hood.
These harnesses
have multi-circuit disconnects for removal of the major assemblies for
maintenance.
e. Protective Control Box (PCB). The PCB used on the HMMWV is similar
to the control boxes used on other military vehicles, with an added
provision for the glow plugs. The functions of the PCB are to energize the
glow plugs, prevent battery polarity reversals, energize the starter
solenoid, and prevent reengagement while the engine is running. The PCB is
mounted behind the instrument panel in the driver's compartment and is
serviced only as an assembly.
f. Circuit Breakers.
Two standard military circuit breakers provide
overload protection on the HMMWV.
These are of the thermal, cycling,
automatic reset type.
Circuits critical to vehicle operation are not run
through circuit breakers.
These are the starter, alternator, and radio
power. The circuit breakers are located on a panel below the dashboard on
the driver's side of the vehicle.
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