Glow Plugs
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Mountain Pass
Joined: Feb 2021
Posts: 134
Likes: 29
From: S.E. TX
Glow Plugs
Are the glow plugs turned on when the key is turned to start? Just wondering because the icons in the panel light up momentarily then go off So if that's when the glow plugs turn on, then the icon goes right back off, how can they actually do any good? This is my first diesel vehicle, having had it now almost 6 years and never thought about but curious how things work.
Cargo Master
Joined: Feb 2015
Posts: 2,338
Likes: 255
From: Livermore Ca.
Wen you first turn on the key, not start. The glow plugs turn on and get hot. In diesels they are mostly for cold weather starts. Diesel has to get hot and diesel motors do that with compression.That is why they don't have spark plugs. What the glow plug does is get very hot so when you start the truck on a very cold morning and all the metal is cold they help bring the temperature of the fuel up so when the motor is on the compression stroke it helps ignite the fuel. The light goes off when the glow plugs are ready to go. After the motor has gotten to a certain temperature they don't come on anymore. I have a 15 and I usually wait for the light to go off before starting my truck but sometimes I forget and she starts anyway. It never gets that cold here where I live. If you live where it gets cold all night than your truck will have a hard time starting if the glow plugs weren't there. I hope this answers your question
Super Moderator
Joined: Aug 2008
Posts: 37,384
Likes: 1,868
From: Frederick, MD
The glow plugs heat to within 2500 degrees within seconds and will stay on as long as necessary.
I just crank and start unless really cold, then I will wait for the light to go out.
If you remote start when really cold you will see a bit of delay there too.
I just crank and start unless really cold, then I will wait for the light to go out.
If you remote start when really cold you will see a bit of delay there too.
Lead Driver
Joined: Nov 2005
Posts: 5,247
Likes: 4,267
From: Kaysville Utah
They go from ambient temps to 1200° C in 2 seconds, So they don't need to be on long to get started to warm up.
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Posting Guru
Joined: Aug 2007
Posts: 1,902
Likes: 26
From: BA, OK
I put the key in the ignition and turn the key to acc, wait for my seat to stop moving forward and by that time the glow plug light goes out then crank it. I know it's not necessary for the 6.7 just a habit I got into starting diesels back in the 90's.
Lead Driver
Joined: Jan 2010
Posts: 6,600
Likes: 84
I don't start it right away either even though the light turns off with the rest of the dash lights. I turn the key to run though but start before the LPFP times out. There is plenty to do before the seat belt such as remove wallet, phone and put in cup holders, turn on my bluetooth Aux adapter so Spotify will work, then flick the key to start.
More Turbo
Joined: Dec 2011
Posts: 572
Likes: 29
1. Turn the key to on without turning the key to start.Do not start the engine until the glow-plug pre-heat indicator turns off.
FTE Legend
Joined: Mar 2017
Posts: 31,968
Likes: 9,197
From: Western NY
Recently, I started the truck away from home and for some reason, forgot to wait (which I normally do as it's a habit) and truck did start. But it ran like dog schit. I shut it off, turned the key and waited for the light to go out, restarted it and ran way better. I forget if it was in the teens or the 20s. IMO, when it's colder out especially, it's good to wait. Like I said, it's habit now so I do it no matter the weather.