Glow Plug System

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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