Bad news big repair

[Hay Dude]

I would look at the relays in the existing system. With two relays does each relay provide power to half the glow plugs.
Or does one do preheat and one do after start heat.
You may wish to ohm out the connections to the relay coil to see if one goes to ground constantly or if they are having constant power applied and switching the ground through the ecm.
If they are standard 5 pin relays get some #22 wire and slip it in the relay coil contacts to see if the relays are being activated. You can look for voltage to be applied to either contact of the relay coil if you have voltage on both pins you will know they are switching the ground with the ecm.
Once you know what they where attempting to do run a wire to the existing relay through a switch to either power or provide a ground.
That should allow you to control the glo plugs and get her started much easier and smoother.

Stop on down.
I can bring beer and great take out food.
Had my ass up in that engine compartment enough….

 

[Hay Dude]

In the 4 hours you've been debating with people trying to help you you could have found out if disconnecting the glow plug buss from its power supply caused the engine to derate.
I'll bet the sensors are all two wire sensors with power and returning signal. The glow plugs are a single connection= power in.
That's how a sensor signal failure CAN derate the engine but an open circuit between the glow plugs and their power supply will not.
I think I'm done here until there is some meaningful information forthcoming.

Repair tech says no, I already asked. That doesn’t mean he’s right though.
Man do you get annoyed at anything/anyone you don’t agree with

 

[IndyJay]

Comes back to earlier discussions on "Right to Repair" and long term ownership ECU based systems.... sorry this doesn't offer any help to HayDude with current problem.

Warranty Claims & Reliability

Agreed. The problem facing the consumers of this compact market segment is the high technology electronics that the federal government has pushed the tractor manufacturers into using to meet their final tier IV emissions standards. If you look at the industry as a whole, all the manufacturers...

www.tractorbynet.com

 

[5030]

Gee, I remember you telling me everything you owned was pre 4. Guess you fibbed. Neither of my M's have a black box, thank goodness.

 

[Hay Dude]

Gee, I remember you telling me everything you owned was pre 4. Guess you fibbed. Neither of my M's have a black box, thank goodness.

What the heck are you talking about?!
An ECU box and emissions aren’t the same. An ECU could be used to do many things- with or without emissions!
I don’t fib.
My 99 Ford Powerstroke had a PCM and no emissions. You don’t know what you’re talking about.

 

[RickB]

Repair tech says no, I already asked. That doesn’t mean he’s right though.
Man do you get annoyed at anything/anyone you don’t agree with

I'm not looking at a $6K repair bill and nitpicking a possible $100 workaround from the sofa.

 

[K5lwq]

I think the same as it monitors the air temp sensor and the water temp sensor

No sir. It can not because that wire is connect to the relay not the ECM. It is just like a fussed wire going straight to the battery. The relay is a switch that makes the connection. The ECM can not handle the amp draw of a glow plug.

However, you can spend your money anyway you wish. I would have put a relay and switch on once I had diagnosed the rest of the circuit was good. This is much more reliable solution than the factory set up.

 

[Hay Dude]

I'm not looking at a $6K repair bill and nitpicking a possible $100 workaround.

Chill out!
Just because I haven’t tried it yet doesn’t mean I refuse to try it. I worked all day and it’s dark and I don’t feel like it right now. It’s sitting outside in the dark.
Besides, repair tech says he thinks it’ll throw a code.
Maybe I will try it…
Talk about impatient, give me a chance and maybe in between all the other crap I have to do, I’ll try it! Maybe someone here knows another way. It’s why I started the thread in the first place!

 

[Hay Dude]

No sir. It can not because that wire is connect to the relay not the ECM. It is just like a fussed wire going straight to the battery. The relay is a switch that makes the connection. The ECM can not handle the amp draw of a glow plug.

However, you can spend your money anyway you wish. I would have put a relay and switch on once I had diagnosed the rest of the circuit was good. This is much more reliable solution than the factory set up.

I’m not saying I won’t. I hit this dead end Friday afternoon. I worked all day today except a few posts on TBN from my Iphone.
Will visit the idea this week.
So try to understand I’m trying to get the factory system working before I install a work around. That’s my first preference. The purpose of the thread was to inquire if there’s anything else I may have overlooked to get the FACTORY system working.

The explanation I was given is that the ECU can detect the failure of the glow plugs. It doesn’t make much sense to me, either since the tractor starts and runs without glow plugs when warm.

 

[Hay Dude]

Something occurred to me that I did not check:

What if the ECU harness plug got moisture in it and corroded contact(s)?
Maybe the glow plug circuit pin is corroded where it plugs into the ECU?

 

[K5lwq]

If having it factory then you are on the right path. However, I am not sure I trust your mechanic. Obviously your computer did not tell you the glow plugs did not work as you did not know until it got colder.

 

[Hay Dude]

If having it factory then you are on the right path. However, I am not sure I trust your mechanic. Obviously your computer did not tell you the glow plugs did not work as you did not know until it got colder.

Correct!
And that’s another really strange thing.…The dealer took a look at what I had already done. I thought maybe they could shed a little more light on the problem, but they didn’t give me much more info.
However, they had an older M125X in with the same problem a few weeks ago. It had No glow plugs, but it DID show a code. They Ohmed everything and tried new sensors- no dice.
They suggested an ECU replacement and $6000 later, the older M125X had glow plugs again.
So the question is, why would the older, but similar size tractor throw a glow plug code, but mine doesn’t?

 

[ptsg]

If you're trying to get the factory system working, then the best thing you can do is to actually get a service manual if you haven't got one already. Then start learning the circuit diagrams and try to figure whatever the ECU needs to see to get the glow plugs going.

 

[Hay Dude]

If you're trying to get the factory system working, then the best thing you can do is to actually get a service manual if you haven't got one already. Then start learning the circuit diagrams and try to figure whatever the ECU needs to see to get the glow plugs going.

I have the shop manual and did consult
I do have to check the ECU plug, though.
Maybe I get lucky and it’s just a cruddy plug or bad pin?
Kubota puts the ECU in a bad place. It’s under the battery in the front of the tractor and seems like it can get wet.

 

[ptsg]

I have the shop manual and did consult
I do have to check the ECU plug, though.
Maybe I get lucky and it’s just a cruddy plug or bad pin?
Kubota puts the ECU in a bad place. It’s under the battery in the front of the tractor and seems like it can get wet.

Could very well be. It's easier and cheaper to check the easy stuff first before throwing out the big bucks for a dealer visit.

 

[Hay Dude]

Could very well be. It's easier and cheaper to check the easy stuff first before throwing out the big bucks for a dealer visit.

I need to check that. Have seen many a harness with green corrosion.
The PCM in my 2008 F-350 was ruined by a leaking windshield. It leaked from the factory. Water ran into an ECM and caused all sorts of wacky things to happen. Horn wouldn’t work, wipers and turn signals would come on at same time, etc.

 

[K5lwq]

Correct!
And that’s another really strange thing.…The dealer took a look at what I had already done. I thought maybe they could shed a little more light on the problem, but they didn’t give me much more info.
However, they had an older M125X in with the same problem a few weeks ago. It had No glow plugs, but it DID show a code. They Ohmed everything and tried new sensors- no dice.
They suggested an ECU replacement and $6000 later, the older M125X had glow plugs again.
So the question is, why would the older, but similar size tractor throw a glow plug code, but mine doesn’t?

This is strange. What are the chances there would be two different models there with the same failure. Sounds more like we understand how bad this is but we just did it for another customer and he is happy. Give us $6000 and we will clean the same connectors for you. Lol

I do hate you have the issue though and hopefully you will find the solution.

 

[Hay Dude]

Yeah that bugs me to no end.
You would think my tractor being newer would store codes more so than an older tractor.
They said the M125x tractors ECU looked like it was under salt water for a couple years. It was all corroded (white dust, green stains, etc).

 

[LouNY]

Stop on down.
I can bring beer and great take out food.
Had my ass up in that engine compartment enough….

Not sure where on down is I thinking you were in the Carolinas.
And as I've gotten older my beer consumption has decreased.
I don't know were they have hide the relays on your Kubota but watching an over weight 70 year old crawl into them could be a sight
to be avoided.

 

[Hay Dude]

Not sure where on down is I thinking you were in the Carolinas.
And as I've gotten older my beer consumption has decreased.
I don't know were they have hide the relays on your Kubota but watching an over weight 70 year old crawl into them could be a sight
to be avoided.

I’m on PA/DE border.
The relays are real easy access.