CHAPTER 2: VEHICLE MAINTENANCE INSTRUCTIONS
TM 9-2350-256-20
2-19 ELECTRICAL TROUBLESHOOTING-Continued
APU LOW OIL PRESSURE SYSTEM-Continued
WARNING
Remove all jewelry such as rings, dog
tags, bracelets, etc. If jewelry contacts a
metal surface a direct short may result in
instant
heating
of
tools,
damage
to
equipment,
and
injury
or
death
to
personnel.
K
Place a jumper wire from wire 27 to terminal of LOW
OIL PRESS lamp. Place red lead of multimeter on
terminal of lamp and black lead to ground. Turn
MASTER and APU FUEL SHUTOFF switches on and
check for voltage. Turn MASTER and APU FUEL
SHUTOFF switches OFF. If voltage is present,
repair/replace wire 420A of APU control box wiring
harness (see paragraph 13-7). If voltage is not
present, replace lamp socket (see paragraph 13-7).
L
Install APU control box (9), four screws (8), four
lockwashers (7), and four nuts (6) to mounting bracket.
Reconnect APU control box to foot dimmer switch and
bulkhead
wiring
harness
to
APU
control
box.
Disconnect bulkhead to APU, master relay, and rigger's
lights wiring harness from bulkhead disconnect. Place
red lead of multimeter on pin C of wire 420A and black
lead to ground. Turn MASTER and APU FUEL
SHUTOFF switches ON and check for voltage. Turn
MASTER and APU FUEL SHUTOFF switches OFF. If
voltage is present, go to step M. If voltage is not
present, repair/replace wire 420A of APU control box to
foot dimmer switch and bulkhead wiring harness (see
paragraph 6-79 for dual voltage; 6-80 for single
voltage).
2-180
