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TM 10-4320-351-14
TABLE 5-1. TROUBLESHOOTING (Continued)
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
a.
Inspect components. Replace as necessary.
6.
Three-inch valved unisex coupling leaks at body or fails to operate properly.
Disassemble and inspect coupling.
Repair or replace faulty components. Refer to paragraph 5.6.
5.2
ELECTRICAL SYSTEM MALFUNTIONS.
Pumping assembly electrical system malfunctions are problems related to the control box, interconnecting cables,
alternator, starter and pumping assembly sensors. Electrical troubleshooting of the pumping assembly is best
accomplished by continuity and voltage checks of the circuitry associated with a reported problem. A system schematic
and a functional description of the electrical system are provided in this section, as well as a system interconnecting
drawing (figure 5-1), as a troubleshooting aid. In addition, the wiring diagrams for the control box, and pumping assembly
cables and wiring harnesses are provided in Appendix J at the back of this manual.
5.3
PUMPING ASSEMBLY PRINCIPLES OF OPERATION. (Refer to figure 5-2.)
When the battery is initially connected to the system through the NATO connector (NATO CONN), 28 VDC is applied:
a.
to the BATT input of VR1, the system voltage regulator.
b.
across circuit breaker CB2 to the auxiliary pump module and the input side of INTAKE HEATER switch S2.
c.
across circuit breaker CB1 to the input side of ENGINE START-RUN-STOP switch S3, shown in the STOP
position.
When ENGINE switch S3 is placed in the momentary START position, 28 VDC is applied from switch terminal 1 to the
starter solenoid, energizing the starter to crank the engine. At the same time, 28 VDC is applied from the output side of
the starter solenoid to the pick up coil of FUEL SHUTOFF SOLENOID L1 on the engine, opening fuel ports to the engine
fuel injectors.
After the engine starts, the ENGINE switch is released to the RUN position. The starter solenoid is deenergized, power is
removed from the starter and FUEL SHUTOFF SOLENOID L1 pick up coil is deenergized. Simultaneously, the alternator
output is applied to the voltage regulator/rectifier where it is rectified to DC and regulated to 28 VDC. The regulator output
at terminal "P" is applied across the EMERGENCY STOP switch to provide electrical power to the system. The regulator
output is also applied through relay K1 to FUEL SHUTOFF SOLENOID L1 hold coil to hold the fuel ports open.
System power is available at the input of FAULT LIGHTS switch S5 any time the system is operating or the ENGINE
START-RUN-STOP switch is in the RUN position. In the BLACKOUT position, no power is applied to the panel lights or
the fault lights. When switch S5 is placed in the ON position, power is applied across dimmer control RI to panel lights
CR1, CR2, CR3 and CR4. The illumination level is adjusted by operating dimmer control R1. All panel lights are Light
Emitting Diodes (LEDs) to assure high reliability and long life.
5-3
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