TM 5-3805-281-24-1
Sub-System Diagnostics
through switch B31 to controller pin 43, causing the
ENGINE COOLANT LEVEL INDICATOR (H20)
indicator to illuminate.
Engine coolant level switch (B6) is a normally open
MONITOR CONTROLLER AND DISPLAY ALARM
switch, held closed when the coolant level is adequate.
(H8)
When closed, the switch applies machine ground to
controller pin 8. The monitor controller only checks the
The monitor controller and display alarm sounds when
status of pin 8 when the fluid level switch (S5) is
the engine oil pressure is low, or the engine coolant
pressed. If ground is present when the switch is
overheats. When the buzzer stop switch (S6) is
pressed, the indicator illuminates.
pressed and released, the buzzer stops sounding and
the buzzer function is automatically reset for the
ENGINE OIL LEVEL INDICATOR (H19)
engine coolant overheat function. The buzzer cannot
be turned off when the oil pressure is low.
Engine oil level switch (B7) is a normally open switch,
held closed with adequate oil level. When closed, the
The buzzer is reset by turning the key switch to OFF.
switch applies machine ground to controller pin 7. The
The buzzer will not sound more than once for the
monitor controller only checks the status of pin 7 when
9015
same problem unless it has been reset.
the fluid level switch (S5) is pressed. If ground is
15
present when the switch is pressed, the indicator
48
CONTROL SWITCHES AND INDICATORS
illuminates.
WIPER SPEED SWITCH (S9)
ALTERNATOR VOLTAGE INDICATOR (H18)
The wiper speed switch is used to select intermittent or
The alternator voltage indicator is controlled by the
continuous windshield wiper operation. The monitor
alternator excitation field voltage monitored by the
controller provides ground switched outputs to the
controller at pin 42. When the alternator excitation field
voltage drops below 10 1.5 volts the indicator
windshield wiper circuit from controller pins 24, 26, 27,
and 28 based on the setting of the wiper speed switch.
illuminates. When the alternator excitation field voltage
goes above 13 1.5 volts the indicator goes out.
If the windshield is open, a ground from windshield
wiper enable switch S14 is allied to monitor controller
pin 6, disabling the wiper speed switch.
CHARGE AIR TEMPERATURE INDICATOR (H15)
WINDSHIELD WASHER SWITCH (S15)
Charge air temperature switch (B12) is a normally
open switch that closes to machine ground when the
charge air temperature exceeds 100C (212F) . The
When the windshield washer switch is pressed, the
monitor controller provides a ground switched output to
machine ground is applied to controller pin 44, causing
the windshield washer circuit from controller pin 25.
the indicator to illuminate.
DRIVE AND WORK LIGHT SWITCH (10)
HYDRAULIC OIL FILTER RESTRICTION INDICATOR
(H21)
The drive and work light switch provides ground
switched outputs to the light circuits. When the switch
The hydraulic oil filter restriction switch (B30) is a
is moved to position 1, controller pin 19 (drive light) is
normally open switch that closes to machine ground
grounded. When the switch is moved to position 2,
when the differential pressure in the hydraulic oil filter
controller pins 19 and 20 (work light) are grounded.
exceeds 15 psi. The machine ground is applied
Continued on next page
CED,OUOE012,27 1926JAN992/3
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