TM 55-1730-229-12
AC 320A0-OMM-00O
TO 35C2-3-473-1
TM 1730-12/1
The ECU includes fault logic which
test grounds as faults, and would shut
closes the fuel shutdown solenoid and
down the engine.
disables the engine ignition unit if any
of the following faults occur:
(5) Temperatures above 160F may
cause damage to the printed circuit
(a) Low oil pressure (less than
Temperature
boards within the ECU.
31 psi) for more than 10 seconds after
sensor S1 is mounted in the electrical
If the
compartment next to the ECU.
the engine reaches 95% rpm.
temperature exceeds 160F, the sensor
(b) High oil temperature (great-
connects dc power to illuminate the
er than 275F) for more than 1 second.
control panel COMPT/GEN HI TEMP caution
This lamp is also illumi-
lamp 1DS11.
(c) Engine speed exceeds 110%
nated when the temperature of the gen-
erator ac windings exceeds limits (sec-
rpm.
tion X).
(d) Loss of speed sensing (no
(6) Control panel INLET FILTER
output from monopole speed sensor) after
BLOCKED caution lamp 1DS8 is illuminated
95% rpm has been reached.
when switch S3 mounted on the engine
(e) EGT exceeds 1300F at en-
The switch is
air-inlet duct closes.
gine speed above 60% rpm, or exceeds
closed when the air-inlet bypass door is
1255F at 100% engine speed.
opened, indicating that the air cleaner
is blocked.
(f) Loss of EGT sensing (no out-
(7) The engine is normally shut
put from thermocouple).
down by setting the ENGINE CONTROL
(g) Current in ECU output cir-
The engine can also be
switch to OFF.
cuits (ignition unit, LCV solenoid, fuel
shut down by setting the MASTER SWITCH
shutdown solenoid, starter contactor K4,
to OFF, opening the GTE 10 amp circuit
or 95% generator enable relay 3K1) ex-
breaker, or pressing the EMERG STOP
ceeds limits for more than 3 seconds.
switch. In any case, the starter latch-
ing relay is unlatched and removes dc
power from the ECU.
(4) If any of the above faults
occur, the engine is automatically shut
down. The ECU fault shutdown latch pro-
d. Fuel Indication System
vides a ground on one of five lines:
LOP, HOT, O/C (overcurrent), O/S (engine
system consists of fuel level sensor
(transmitter) MT1, low fuel level sen-
overspeed), and O/T (EGT overtempera-
sor switch S4, low fuel pressure sensor
This ground illuminates the
ture).
switch S5, resistor TB1-R1, zener diode
appropriate control panel fault lamp.
TB1-CR1, meter 1M3, and indicator lamps
The ground is latched on until dc power
1DS5 and 1DS6. Maintenance of the fuel
is removed from the ECU. Diodes TB3-CR3
sensors (all located in the fuel tank)
through CR8 are connected in the fault
lamp circuits to prevent the ECU from
is covered in section XI.
shutting down the engine during a lamp
test.
As described in paragraph b, a
FUEL meter 1M3 indicates the fuel level
ground is applied to the negative ter-
in the tank. When the MASTER SWITCH is
minals on the fault lamps when the PRESS
ON, dc power is applied via current
TO TEST switch is pressed.
limiting resistor TB1-R1 to the meter
If diodes
Zener diode limits
TB3-CR3 through CR8 were not present,
positive terminal.
the ECU fault logic would see the lamp
the voltage across the meter to 5.1
