TROUBLESHOOTING THE HMMWV - OD1616 - LESSON 1/TASK 2
(5) 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 re-engagement 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.
(6) Circuit Breakers.
Two standard military circuit breakers
provide overload protection on the HMMWV.
These are 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.
(7) Driver's Compartment.
The driver's compartment contains
vehicle control indicators, and a removable instrument cluster. The
cluster contains gages that monitor the engine temperature, oil
pressure, fuel level, vehicle speed/mileage, and battery voltage
through sending units, except the speedometer and voltmeter.
Also,
on the removable cluster is the hi-beam indicator. The WAIT TO START
and BRAKE indicators are located to the left of the steering wheel on
the dash.
(8) Brake Indicator.
The BRAKE indicator illuminates when a
system hydraulic failure occurs or when the parking brake is engaged.
A parallel circuit is formed through the parking brake switch and the
proportioning valve switches if either or both switches are closed.
(9) Vehicle Lighting System.
With the development of a
satisfactory electrical system, electric lighting has become the
standard means of lighting motor vehicles.
The lighting system on
the HMMWV is a standard military system in which a main switch
controls the service headlights, blackout lights, directional signals
and the panel lights. When the panel is illuminated, a lamp in the
transmission quadrant illuminates the position of the shift lever
indicator. The directional signal switch is also a standard military
unit.
A solid state flasher located under the dash next to the
circuit breakers pulses the directional lamps and provides a hazard
flashing feature.
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