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Tractor Help - Glow Plugs not preheating(?).

woods

woods

I probably did it wrong.
Joined
May 22, 2020
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5,165
2001 Kubota L3710

I know very little about diesels, so bear with me.

How its always worked, turn the key to the run position, leave it there for a second or two until the dash lights goes off, then crank. When its colder, dash light stays on for a bit longer.

Well, the dash light hasn't been kicking on. I figured it was just warm enough it didn't need to preheat them or not; whatever the term is. I tried it recently with it in the 30s, still no dash light it is a bit harder to crank over.

Replaced the glow plug relay yesterday, no change. Swapped the bulbs on the dash, that socket still not light up so the bulb is good.

Where else should I be looking? Glow plug relay gets sucked into the main harness and not sure where it gets spit out. There another common at fault place to look?

There's a thin metal plate deal that bridges the tops of all the glow plugs; is that supposed to get power with a test light?
 
the thin metal plate deal is the bus bar that connects the glow plugs to the 12V.
You need 12V there.

can you turn the key opposite to manually light them? That's a thing in some of those key switches. See if the light comes on if you do that.
 
Chasing the same problem on a Cat midi ex.. you should have a glow plug timer that triggers the relay to heat the glow plugs for x amount of time.
 
87manche said:
the thin metal plate deal is the bus bar that connects the glow plugs to the 12V.
You need 12V there.

can you turn the key opposite to manually light them? That's a thing in some of those key switches. See if the light comes on if you do that.
Click to expand...
I've never paid attention to my JD if it heats the plugs with the key in just the ON position. I've just assumed you have to turn and hold it counterclockwise to heat them. Same as my old MF. Guess I'll have to try it next time I start it....though even down to around freezing it never needs plugs and fires on the first crank so :confused:
 
87manche said:
the thin metal plate deal is the bus bar that connects the glow plugs to the 12V.
You need 12V there.

can you turn the key opposite to manually light them? That's a thing in some of those key switches. See if the light comes on if you do that.
Click to expand...
ok, so if I ground the test light it should light up if I tag that plate then. I tried and got nothing.

Key doesn't turn in the opposite direction. There's "off", "run"- that heats the plugs, "start"- then flips back to "run".
 
LittleMan said:
Chasing the same problem on a Cat midi ex.. you should have a glow plug timer that triggers the relay to heat the glow plugs for x amount of time.
Click to expand...
yep, that used to be the case. I thought it was connected to the temp sensor coming off the t-stat housing. If it registers that its warm enough, that will dictate how long it stays on before start. I messed with the wiring and nothing.
 
woods said:
ok, so if I ground the test light it should light up if I tag that plate then. I tried and got nothing.

Key doesn't turn in the opposite direction. There's "off", "run"- that heats the plugs, "start"- then flips back to "run".
Click to expand...
Buy a half decent multimeter and get familiar with it.

To successfully use a test light you need to already have a good amount of electrical kung-fu.
 
Have you checked fuses? If the relay fried or you have a shorted glow plug it’ll blow the fuse and it should for sure have a high amp fuse like 30A or more.
 
Muckin_Slusher said:
Buy a half decent multimeter and get familiar with it.

To successfully use a test light you need to already have a good amount of electrical kung-fu.
Click to expand...
yea, I have a $50 from HF. test light is just easier. I was simply just checking if they were getting power at all.
 
My old New Holland doesn’t have a relay, you turn the key to the left and count. I do 6 seconds if it’s warm out. 12 if it’s cold AF. The kubota has a timer and light like your talking about.
 
JR4X said:
Have you checked fuses? If the relay fried or you have a shorted glow plug it’ll blow the fuse and it should for sure have a high amp fuse like 30A or more.
Click to expand...
There's like four fuses on this thing, unless I'm missing something. lights, ignition, and one other thing. there isn't much there.

I did read the following:
"Its running good again, first of all i would like to thank very much everyone who helped me out and gave me ideas on TBN. without them i probably still would be lost. Ok so now i get to explain what the problem was.... the first glow plug by the output shaft was shorting out causing all the other plugs to not even work and eventually that one burnt out and didnt work at all, so i took out the one right next to it and found out it works great, i put it back in and then disconnected the one that was shorting out and bypassed it so basically the other three were the only ones connected, preheated for 20 seconds and it fired up first try, even on 3 preheated cylinders, so now i have to spend the 15 dollars on a new glow plug and replace it wich takes me about 5 minuits, im glad it wasnt a big problem"

So perhaps I'll check to see if if the issue starts there. That first plug sort of sucks because its tucked right under the gas tank and its a bitch to get in there.
 
sounds like it's getting cold there and your tractor wants to be hibernating
 
Find a manual and look for fuses first, it'll be the easiest thing to fix. That metal strip should have 12v when the plugs are on. If you're not getting anything start following wires back from the bar and test things until you find a problem

On my 2000s Deere you turn the key to on and then push it in to run the grid heater
 
ok, I'll start at the metal strip. see if I'm getting anything. the test light didn't even come on, but I'll use a multimeter instead. from there I'll work backwards.
 
woods said:
There's like four fuses on this thing, unless I'm missing something. lights, ignition, and one other thing. there isn't much there.

I did read the following:
"Its running good again, first of all i would like to thank very much everyone who helped me out and gave me ideas on TBN. without them i probably still would be lost. Ok so now i get to explain what the problem was.... the first glow plug by the output shaft was shorting out causing all the other plugs to not even work and eventually that one burnt out and didnt work at all, so i took out the one right next to it and found out it works great, i put it back in and then disconnected the one that was shorting out and bypassed it so basically the other three were the only ones connected, preheated for 20 seconds and it fired up first try, even on 3 preheated cylinders, so now i have to spend the 15 dollars on a new glow plug and replace it wich takes me about 5 minuits, im glad it wasnt a big problem"

So perhaps I'll check to see if if the issue starts there. That first plug sort of sucks because its tucked right under the gas tank and its a bitch to get in there.
Click to expand...
pull the metal bus bar from the top of the plugs.
Ohm out the glo plugs to the block individually.
Should be a few ohms, not infinite and not 0. I'd expect them to all be similar ohms unless one is bad.
 
and you're welcome:



part two contains the electrical system .
glo plugs is 9-M6

edit:
lists a glow controller and a glow relay. The controller is probably what makes it temperature sensitive.
I'd have a hard look at it. Probably what's failed. My guess is bimetallic bits that make it temperature dependent for how long it glows.
but that's just a guess.
Look at the diagrams.
 
so apparently it gets a reference from the water temp sensor and then operates the relay based on that.
 

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87manche said:
so apparently it gets a reference from the water temp sensor and then operates the relay based on that.
Click to expand...
Ah, that's the bit I was looking for. I undid the wire that comes off the t-stat. All looked fine. I followed the wires and it goes into the harness that's covered. Not sure where to look from there.
 
 
So, from here:


jfghdfyrtytr.png


mine's the same. the relay is on the backside of that panel. I guess one of those is the controller then.
 

16415-65660 Kubota​


That's the controller part number. I'll check that out as well.
 
akguy09 said:
Did you check the OHMS in the glow plugs to make sure that they are working?
Click to expand...
Not yet. I just did a quick test on the metal bar that bridges them with a simple test light, and got no power at all. So I think its before it gets to the plugs.
 
Is that bar bare metal? On my New Holland it was painted blue after it was all put together. I had to take it apart and buff the paint off so I could test it.

An 01 seems new enough that I’d think it has to have a fuse for the glow plugs.
 
JR4X said:
Is that bar bare metal? On my New Holland it was painted blue after it was all put together. I had to take it apart and buff the paint off so I could test it.

An 01 seems new enough that I’d think it has to have a fuse for the glow plugs.
Click to expand...
Looked bare. Has a almost yellowish tinge to it.
 
In on this one…. I think my kubota is doing the same thing…. Red glo plug light never goes off until it’s started.…. But a yellow one comes on below it, while key is in start position….. turns back off once started and keys back in run position.
 
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