4-13. TROUBLESHOOTING (CONT)
TEST OR INSPECTION
APU - CONT
GLOW PLUG HEATS SLOWLY OR FAILS TO HEAT - CONT
For lamp-type glow plug indicator, hold starter switch in GLOW position for more than 5 seconds.
Glow plug indicator will light, remain lit for about 5 seconds, and then extinguish. Observe a, b, or c:
a. If glow plug does not heat up, use multimeter to check for +12 Vdc at glow plug terminal with
respect to engine or frame. If voltage is present, replace glow plug. If voltage is not present,
proceed to step 3.
b. If glow plug indicator does not light, check bulb, electrical connections, and timer.
If glow plug indicator lights and does not extinguish in approximately 5 seconds, replace timer.
Check APU wiring harness for broken, corroded, and burned wiring and loose electrical connections.
Using an electrical tester (multimeter) (item 17, appx. B) and APU electrical schematic (figure FO-4),
check APU control box for defective starter switch.
APU JUMP START SYSTEM INOPERABLE
Check jumper cables for loose clamps and connectors, fraying and corrosion, kinks, and damage.
Change 1 4-31