TM 9-2320-280-20-1
2-31. GLOWPLUGS CIRCUIT TESTS (PROTECTIVE CONTROL BOX)
These tests of the Glowplugs Circuit can be run anytime you think there may be a
problem with the glowplugs, or if you were sent here from another test.
If you were sent from another test, be sure to mark where you came from so you will be
able to return.
If you are running this test because the engine is hard to start when cold, remember that
there is also a cold start advance circuit (part of the fuel system) which is not checked
here.
For any starting problem, we recommend running the “STARTABILITY” test chain just
to be sure you don't miss anything.
At the bottom of this page is a simplified block diagram which shows how the different
parts of the glowplug circuit depend on each other and on other engine circuits.
Refer to fold-out page FO-9 and leave it open for reference while preforming these tests.
The fold-out diagram is arranged to allow you to follow the diagnostic logic and
understand what you are testing, when and why.
ALTERNATOR A.C.
LEAD
INSTRUMENT POWER
GLOWPLUG
CONTROLLER
PROTECTIVE
CONTROL
BOX
WAIT-TO-START
LAMP
GROUND
GLOWPLUGS CIRCUIT SIMPLIFIED BLOCK DIAGRAM
FOR PROTECTIVE CONTROL BOX
BATTERY
ALTERNATOR
Change 1 2-303
GLOWPLUGS
