TC25 Glow Plug Operation

[TORQUIN]

I have a TC25 I am working on and I need to know how the glow plugs operate on this tractor. The only time they seem to be energized is when the engine is turning over, and that is odd to me, as my Kubota operates the glow plugs when you turn the ignition on, for 5 to 15 seconds, depending on temperature.
I checked and the relay seems to be working, as I am getting 10.5 VDC to the glow plug buss rail when turning the engine over. I saw something about a timer in the parts manual, but if it exists on the tractor, it isn't in the location the book says it is. I did see three relays along the right side of the console, behind the panel.
So, my questions are,
1. should the glow plugs operate when you turn the key on?
2. Where is the glow plug timer?

Thanks,
Chris

 

[tmeric7]

I'm speaking from experience with my TC29DA. I think it's safe to assume the answers will apply for you. I know that other models operate like I'm about to describe.

1. Yes, the GP should energize for a certain amount of time when the key switch is turned to ON. My model is 10 seconds. I think others are 4.

2. It is under the right cowl below the relays. See my pics.

I replaced my timer relay about 2 years ago and I posted here on TBN about it. You could search my message history. It has part numbers, for my tractor.

 

[TORQUIN]

I have found, after purchasing a service manual, that this model does not have a glow plug timer, and, if you can believe this, the manual does state that the glow plugs are supposed to be active while it is turning over. There is reference to a preheat relay, but no timer in the manual text or wiring diagram for this "economy" model.
I, however, am looking to add one to it, since I believe it will not be that difficult.
I will go hunt for your old thread.

Thanks,
Chris

 

[RjCorazza]

This TBN thread indicates that the TC25 has a 4 position switch, with Off / Run / Glow / Start. If correct, you would hold the key switch in the position just before it would crank. The Glow indication light should lite when the key is advanced far enough.
https://www.tractorbynet.com/forums/threads/tc-25-questions.259832/

My first diesel had a similar manual Glow operation, but I turned the key backwards for Glow, forward to run forward again to start.

 

[TORQUIN]

This TBN thread indicates that the TC25 has a 4 position switch, with Off / Run / Glow / Start. If correct, you would hold the key switch in the position just before it would crank. The Glow indication light should lite when the key is advanced far enough.
TC-25 Questions

My first diesel had a similar manual Glow operation, but I turned the key backwards for Glow, forward to run forward again to start.

Yes, I have been trying to reconcile that, to no avail. Even the service manual implies that there are 4 positions. There are only 3 positions in this ign switch. While it does appeasr to a be stock switch, it does not say NH on it, but I don't know if this part would be an NH brand, so I can't count on that to say one way or the other. It does not engage the glow plugs when in between run and start, even with no detent.
I am familiar with a switch that turns to the left for glow plugs, as my Dad's IH 234 had this type of glow plug operation.
Currently, I have a new ign switch on order because the existing one does not engage the starter circuit but does engage the glow plugs, in the start position. I will be installing a regular ignition switch, about 6 times cheaper than NH brand. Additionally, I am looking at installing a glow plug timer that engages when the ign switch in in the run position, for around 10 seconds.
Still working on the actual design of the timer setup.

Thanks,
Chris

 

[RjCorazza]

Sounds like you have a plan to get it all like it really should have been originally designed. That would make a good write-up for future users wanting a timer on the glow plugs.
My current tractor has the glow plugs that turn on in the run position controlled by the ECU based on ambient temp. I prefer manual glow plug activation that MY computer controls.

 

[TORQUIN]

I am trying to decide between a dedicated glow plug timer, as mentioned in this thread, TC29: how I added glow plug button and sorted out timer relay, vs a timer that I can program any way I like, https://www.amazon.com/dp/B0B664VDW...p_csd=d2lkZ2V0TmFtZT1zcF9kZXRhaWxfdGhlbWF0aWM, possibly with a temperature sensor that will account for ambient temp also.
The universal timer would control the glow plug relay, so no worries about current draw through it.

Thanks,
Chris

 

[rjok]

I am trying to decide between a dedicated glow plug timer, as mentioned in this thread, TC29: how I added glow plug button and sorted out timer relay, vs a timer that I can program any way I like, Amazon.com, possibly with a temperature sensor that will account for ambient temp also.
The universal timer would control the glow plug relay, so no worries about current draw through it.

Thanks,
Chris

I have a 1999 TC-33 that works just like your wiring shows. I hold the ignition switch between the run and start positions and the glow plug light will come on. I usually hold it for about 20 seconds when it's cold. It even requires a little heat when it's warm. Rick

 

[tmeric7]

I have found, after purchasing a service manual, that this model does not have a glow plug timer, and, if you can believe this, the manual does state that the glow plugs are supposed to be active while it is turning over. There is reference to a preheat relay, but no timer in the manual text or wiring diagram for this "economy" model.
I, however, am looking to add one to it, since I believe it will not be that difficult.
I will go hunt for your old thread.

Thanks,
Chris

Gotcha, and that makes sense after reading your other thread. So there are multiple ways you could go, it seems. I like my added button because, apparently like your stock system, you can run the plugs however long you think is needed before trying to start. With the timer, you get the factory preset only.

Also, on my model with the timer "feature" the plugs are energized during starting too.

Tristan

 

[thclimer]

My TC33D utilizes a timer for the glow pugs and as tmeric7 indicated they are also energized during the engine cranking sequence.

If this TC25 did not come with a glow plug timer I think I'd go with the push button option. The only thing I'd be curious about is how long to energize the glow plugs as I would imagen too long might damage them? I've read where some tractors can be on as long as 20 seconds. The timer on my glow plugs is only about 5-6 seconds. Sometimes when it really cold (single digits F) I'll initiate the glow plug cycle twice before cranking the engine.