CHAPTER 2: VEHICLE MAINTENANCE INSTRUCTIONS
TM 9-2350-256-20
2-19 ELECTRICAL TROUBLESHOOTING-Continued
APU ENGINE OIL PRESSURE GAGE CIRCUIT-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 Install APU control box (9), four screws (8), four
lockwashers (7), and four nuts (6) to mounting bracket.
Open air inlet doors (TM 9-2350-256-10). 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 E 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 L. If voltage is not present, repair/replace wire 420
of APU control box to foot dimmer switch and bulkhead
wiring harness (see paragraph 6-79 for dual voltage; 6-
80 for single voltage).
L Reconnect bulkhead to APU, master relay, and rigger's
lights wiring harness to bulkhead disconnect. Open
center-front air inlet doors (TM 9- 2350-256-10).
Disconnect bulkhead to APU, master relay, and rigger's
lights wiring harness from APU engine disconnect.
Place red lead of multimeter on pin A of wire 420 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, notify Direct Support Maintenance. If
voltage is not present, repair/replace wire 420 of
bulkhead to APU, master relay, and rigger's lights wiring
harness (see paragraph 6-75 for dual voltage; 6-76 for
single voltage).
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