How to test glow plugs? - Chevy and GMC Duramax Diesel Forum
01-04.5 LB7 Duramax Powertrain Discussion of components that are directly involved in the power production and all that is needed to get and keep the truck moving . Engine , Transmission, Etc.

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post #1 of 5 (permalink) Old 10-06-2011, 09:15 PM Thread Starter
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How to test glow plugs?

hey my truck is throwing a p0380 code... which means a bad glow plug or controller. how is the best way i can test for this? when i fire it up and its cold (like 50* or colder) i have one of my cylinders that has quite a bit higher injector balance rate, but once it warms up, its just like all the others. Is that a sign that possibly my cylinder #1 glow plug is the bad one? or what is the best way to test to see which one(s) need replaced?

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post #2 of 5 (permalink) Old 10-06-2011, 10:55 PM
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as you said, p0380 usually indicates 1 or more bad glow plugs, g/p controller, or the 175 amp fuse. check the glowplugs first. take the rail off of them and get a test light, hook it to the pos side of the battery and touch the tip of each glowplug. if it lights up the glowplug is bad.

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post #3 of 5 (permalink) Old 10-07-2011, 07:19 PM
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What he said^^^^

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post #4 of 5 (permalink) Old 10-07-2011, 07:45 PM
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great advice! Thanks


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post #5 of 5 (permalink) Old 03-06-2016, 03:43 PM
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I know this is an old thread but when I cold start my lb7 it runs rough smokes a little bit then stops smoking after a minute and after truck warms up it smoothes out I checked rail pressure and balance rates all look good I'm going to change fuel filter and all my glow plugs are new by the way I have a friend with a lly that said his module went out on his with no code so I'm just curious if anyone has any ideas by the way my truck has no codes and doesn't smoke or rough idle when fired up while motor is still warm or plugged in
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