CHAPTER 2: VEHICLE MAINTENANCE INSTRUCTIONS
TM 9-2350-256-20
2-19 ELECTRICAL TROUBLESHOOTING-Continued
APU STARTING 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.
D
Reconnect bulkhead to APU, master relay, and rigger's
lights wiring harness to APU engine disconnect. Open
air inlet doors (see TM 9-2350-256-10). Disconnect
bulkhead to APU, master relay, and rigger's lights
wiring harness from bulkhead disconnect. Place a
jumper wire from pin B to socket B. Place red lead of
multimeter in socket J of wire 65 and black lead to
ground. Turn MASTER and PREHEAT switches ON
and check for voltage. Turn MASTER and PREHEAT
switches OFF. If voltage is present, repair/replace wire
65 of APU control box to foot dimmer switch and
bulkhead wiring harness (see paragraph 6-79 for dual
voltage; 6-80 for single voltage). If voltage is not
present, reconnect bulkhead to APU, master relay, and
rigger's lights wiring harness to bulkhead disconnect
and go to step E.
E
Disconnect APU control box to foot dimmer switch and
bulkhead wiring harness from APU control box.
Remove four nuts (1), four lockwashers (2), and four
screws (3), and release APU control box (4) from
mounting bracket. Remove four screws (5) and four
lockwashers (6), and release rear panel (7) from APU
control box. Reconnect APU control box to foot
dimmer switch and bulkhead wiring harness to APU
control box. Disconnect wire 65 from START switch.
Place red lead of multimeter on terminal of START
switch and black lead to ground. Turn MASTER,
PREHEAT and APU START switches ON and check
for voltage. Turn MASTER, PREHEAT and APU
START switches OFF. If voltage is not present, go to
step F. If voltage is present, repair/replace wire 65 of
APU control box wiring harness (see paragraph 13-7).
2-164