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How long SHOULD glow plugs last?
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=92054
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Author:  WWDiesel [ Tue Sep 14, 2021 10:05 pm ]
Post subject:  Re: How long SHOULD glow plugs last?

All very good and legitimate questions that we would all love to know the answers to.
If we had the data for the maps for the ambient temperature vs glow plug cycle times, vs voltage, we could build a graph of it and maybe get a little better understanding of how it functions and is controlled. :banghead:

Author:  krb [ Fri Sep 17, 2021 7:36 am ]
Post subject:  Re: How long SHOULD glow plugs last?

The way I understand it and what little I've noticed and remember from last winter (only driven in two winters) is that the glowplug icon lights up in the dash below a certain temp. Wait til it goes off & start. Sometimes when it was real cold out (teens & twenties here) I'd cycle it twice, just for the fun of it.

Author:  user113 [ Sun Sep 19, 2021 4:44 pm ]
Post subject:  Re: How long SHOULD glow plugs last?

Here's a video I just ran across from ID parts: https://www.youtube.com/watch?v=SYWHx65elCU&t=189s

Author:  user113 [ Sun Sep 19, 2021 5:04 pm ]
Post subject:  Re: How long SHOULD glow plugs last?

user113 wrote:
Here's a video I just ran across from ID parts: https://www.youtube.com/watch?v=SYWHx65elCU&t=189s


So, if the "module" is nothing more than a relay, then it would seem the ECM is actually controlling the voltage.

Author:  WWDiesel [ Sun Sep 19, 2021 9:11 pm ]
Post subject:  Re: How long SHOULD glow plugs last?

user113 wrote:
user113 wrote:
Here's a video I just ran across from ID parts: https://www.youtube.com/watch?v=SYWHx65elCU&t=189s

So, if the "module" is nothing more than a relay, then it would seem the ECM is actually controlling the voltage.

Yes, it is a very different type of
relay/module and is controlled by the ECM based on programing/maps stored in the ECM's memory.
I am sure Yeti, aka Marco Giacomelli, could better explain in detail how the maps are programed for control of the GP module and ultimately the Glow Plug Voltage and time spans.
.

Author:  layback40 [ Mon Sep 20, 2021 7:14 pm ]
Post subject:  Re: How long SHOULD glow plugs last?

user113 wrote:

So, if the "module" is nothing more than a relay, then it would seem the ECM is actually controlling the voltage.



I suspect the ECM just provides a switching voltage, that is, its on for a part of the time at 12v and off the remainder of the time. Doing this at a reasonable frequency would result in an average voltage of about what is set.
I wonder what would happen if some one removed the ECM supply and replaced it with a 12v supply from the battery?
A part from shortening GP life, they would heat up quicker.

Author:  WWDiesel [ Mon Sep 20, 2021 10:41 pm ]
Post subject:  Re: How long SHOULD glow plugs last?

Quote:
I wonder what would happen if someone removed the ECM supply and replaced it with a 12v supply from the battery?

You would probably burn them out in short order. They cannot withstand 12v for any length of time.

From manual:
When the ignition is turned on, the ECM activates the glow plug relay for a time period that is determined by engine coolant temperature, atmospheric temperature and battery voltage.
The GP module/relay is wired 12v hot all the time, the voltage going to the glow plugs is pulsed by the ECM based on the 3 above input values it receives.
The module is pulsed by the ECM via a grounding circuit and feedback it receives from the GP module.
Adding a manual switch would be of no use since is already supplied 12v all the time.
See wiring schematic.

Image

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