HDC Control Box power-up and operation.
Do not activate the vehicle's hydraulic control levers or depress any buttons on the HDC
control box unless directed by this procedure. Failure to comply could result in serious
injury or death to personnel.
Ensure vehicle power is off.
Remove HDC Control Box and umbilical cable W4 from stowage location behind operator's seat.
Place HDC Control Box in operating location.
Connect HDC Control Box and umbilical cable W4 to vehicle as per (WP 0004).
Place vehicle power on.
Ensure parking brake is on and transmission is in neutral, then start vehicle engine. HDC System will not
receive operating power from vehicle unless parking brake is on and transmission is in neutral.
With the vehicle engine running and the transmission in neutral, turn the HDC Control Box on by pressing
the POWER button. (Depressing the POWER button again will turn the HDC Control box off.) Note that:
Power to the HDC System is disconnected if the vehicle is taken out of neutral.
The solenoid valves will return to their normal vehicle operating positions (de-energized/not
powered) when the HDC Control Box is turned off (or power is disconnected).
The HDC System automatically initiates a start-up Built-In-Test (BIT) when power is
applied to the system.
After power is applied to the HDC System, and a start-up BIT is performed, if a BIT fault message is
displayed on the Liquid Crystal Display (LCD), do not use the HDC Control Box for testing.
When system powers up, displays will be dark for 3 seconds. If significant sections of the displays are
missing, displays will be unreadable; do not use if displays are unreadable.
If the temperature is below -4°F (-20°C), the displays will not come on until warmed up. The power light
will blink until the displays have warmed up.
If the start-up BIT passed, and the HDC System is operating properly, the initial default display for the
status of the HDC System solenoid valves will appear as shown in Table 1. This is the normal de-
energized (unpowered) state of the HDC System solenoid valves.
Confirm that the HDC Control Box displays the pressure transducer number, hydraulic line pressure,
solenoid valve number, valve power status (on/off) (PWR), and valve position (open/closed) status similar
to Table 1 (for the solenoid valves). (Note: a CIRCUIT FAULT message indicates a disconnected or
malfunctioning wire harness, electrical cable, or defective component. Check all connections in the event
of a CIRCUIT FAULT message as shown in the test display example on Figure 2).