APU CONTROL BOX JUMPER WIRES AND TIMER HARNESS
This task covers:
General mechanics tool kit, item 16, appx. B
The following tools can be found in common tool kit no. 2, item 18, appx. B:
Electrical repair kit
Extension light, 24 ft
Electrical insulation sleeving, item 22, appx. E
On APU with APU engine serial number 504697 and subsequent, the glow plug
indicator is changed from a glow-type indicator to a lamp driven by a timer.
Open cover to APU control box by lifting up retainer (1) and lowering cover weldment (2).
Remove four screws (3), lockwashers (4), and access plate (5) from APU control box. Discard lockwashers.
Using APU electrical schematic (figure FO-4) as a guide, tag and disconnect jumper wire (6) from starter switch
(7) terminal B.
Cut existing heat shrink tubing and disconnect diode (8) from jumper wire (6) and APU wiring harness (9).
On glow-type glow plug indicator only, tag and disconnect jumper wire (10) from starter switch (7) terminal GL and
glow plug indicator (11).
On lamp-type glow plug indicator, unplug timer harness connector (12) from timer (13). Unplug timer harness
wires (12) from glow plug indicator (14).
Using APU electrical schematic (figure FO-4) as a guide, tag and disconnect timer harness wires (12) from starter
switch (7) terminals GL and ST.
4-130 Change 1