TROUBLESHOOTING THE M998 ELECT SYST. - OD1617 - LESSON 1/TASK 2
engine temperature), the engine can then be started.
After the
engine is started, the glow plugs will continue to cycle (for up to 5
minutes), then stop cycling.
The glow plug system is cycling normally when there is an on pulse
for 1 second and an off pulse for up to 15 seconds. To detect glow
plug system cycling, watch the voltmeter; the gage needle will move
to the left when the glow plugs are on, then return to its normal
position when the glow plugs are off. Also, a relay click should be
heard from the protective control box as the system switches on and
off. A multimeter may be used on any glow plug wire to observe the
operation of the glow plug system.
If the glow plugs continue to
cycle after the engine has been warmed up, the most probable cause is
the alternator, which would then be checked.
If engine temperature is above 120 F, the glow plugs are not required
to start the engine.
While reading through these paragraphs
concerning troubleshooting the glow plug system, refer to figure 9 on
the following page.
In this task, as with task 1, the reference
quotes "the TM" will refer to TM 9-2320-280-20, unless otherwise
stated.
NOTE
Allow the engine to cool for 10 to 15 minutes
before
performing
any
glow
plug
resistance
checks.
a.
Malfunction:
GLOW PLUG SYSTEM DOES NOT OPERATE PROPERLY ON
INITIAL START-UP (ENGINE CRANKS NORMALLY, ENGINE MECHANICALLY SOUND,
FUEL SYSTEM OPERATING NORMALLY.)
Step 1.
Remove the wiring harness connectors from all the glow
plugs. Using a multimeter, check the glow plug resistance. Replace
any glow plug not having 1.5-2.5 Ohms resistance. When replacing the
glow plug(s), follow the procedures contained in paragraph 3-38 of
the TM.
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