APU Engine Oil Pressure Gage Circuit
APU engine oil pressure gage fails to operate. Do steps 1 thru 12.
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.
Disconnect APU control box to foot dimmer switch and bulkhead wiring harness from APU control
box. Place red lead of multimeter in socket N, wire 419 and black lead to ground. Turn MASTER
switch on and check for voltage. Turn MASTER switch OFF. If voltage is present, go to step 4. If
voltage is not present, go to step 2.