Bad news big repair

[MossRoad]

Thanks for adding some sanity.
you can post questions or replies while wrenching, working, eating, etc.
Just like I did today.

Yep. At my job current job sometimes I have to watch glue dry! Seriously.
Watch
Glue
Dry
Yikes.

So get out the phone and see what's up with the world.

I have other tasks where I have to wait 5-10 minutes at a time. Like if I have to do a repair in an occupied space, but have to wait for it to be unoccupied. You have to stand and wait. Nothing else to do. 5 more years of that and I retire again.

 

[milkman636]

It seems odd that only one function is failing if the ECU is bad. I’m more inclined to think that the ECU is not getting all the necessary inputs needed to determine that the glow plugs should cycle. Temp sensors are typically resistive inputs, they should have a linear change in resistive value over a specific temperature range. Sensor manufacturers typically offer a chart that lists proper resistance values for given temperatures. Does the service manual cover checking the temperature sensors for accuracy of the temperature inputs? Is there any kind of summary in the service manual that lists all the inputs into the glow plug cycling decision? Does the manual have any diagrams that detail the glow plug circuits? Or whether or not there is wiring connected in parallel that could monitor glow plug circuit integrity?

I like making things work as designed too. If I lived anywhere nearby I’d stop in and offer a hand. I’m sure there are others here that would be willing to help also. Not having a similar tractor or access to relevant manual sections does limit our usefulness though.

 

[MossRoad]

Clean up all your grounding spots too, a poor ground can do strange things !

Not what we're looking for here but a solution I have seen for this type of problem was to put a tee in the heater hoses with a valve and quick couplers and a matching set up in a work truck. Farmer or logger pulls up, hooks up and circulates the hot coolant from the pickup through the cold diesel, drink a cup of coffee and fires up the grumpy diesel.
I always thought it would shock the cold block having that hot coolant hit it but have seen it done for years.

Wow! That's beautiful. Never heard of that before.

 

[MossRoad]

It seems odd that only one function is failing if the ECU is bad. I’m more inclined to think that the ECU is not getting all the necessary inputs needed to determine that the glow plugs should cycle. Temp sensors are typically resistive inputs, they should have a linear change in resistive value over a specific temperature range. Sensor manufacturers typically offer a chart that lists proper resistance values for given temperatures. Does the service manual cover checking the temperature sensors for accuracy of the temperature inputs? Is there any kind of summary in the service manual that lists all the inputs into the glow plug cycling decision? Does the manual have any diagrams that detail the glow plug circuits? Or whether or not there is wiring connected in parallel that could monitor glow plug circuit integrity?

I like making things work as designed too. If I lived anywhere nearby I’d stop in and offer a hand. I’m sure there are others here that would be willing to help also. Not having a similar tractor or access to relevant manual sections does limit our usefulness though.

Well, think about it. Each function is controlled by different sections on the ECM. If one component fails in a section, the rest of it can continue to operate.

 

[number two]

Clean up all your grounding spots too, a poor ground can do strange things !

Not what we're looking for here but a solution I have seen for this type of problem was to put a tee in the heater hoses with a valve and quick couplers and a matching set up in a work truck. Farmer or logger pulls up, hooks up and circulates the hot coolant from the pickup through the cold diesel, drink a cup of coffee and fires up the grumpy diesel.
I always thought it would shock the cold block having that hot coolant hit it but have seen it done for years.

I had thought about posting the same idea since I've seen loggers doing this 15-20 years ago.
Too bad so many posters have not really read the issue and inject the same ideas over and over.

 

[MHarryE]

This might be really stupid -I’m prepared for that. When I had one, I kind of remember part of the priming procedure was to disconnect the glow plug at the front , in front of cooling system up high. Reason not to toast the glow plugs during the multiple switch on 30 seconds, off 30 seconds, etc. my manual went with the tractor 5 years ago when I traded. Not sure if it was disconnect at relay or 60 amp slow blow fuse. I’m sure it’s stupid because you already changed that out but it rang a bell with me that I screwed something up going through this procedure. But I think there is a w/y wire out of the ECM that feeds the relay. Need battery voltage from there when cold, if no voltage then it’s ECM or temp sending unit and I think you already changed all the easy stuff. The jury rig is easy but I’m with you - would want it to work like intended just like your 126.

 

[Racenut]

Glow plugs wont heat if it's not cold enough.. do you know where the temp sensor is that determines that? a) is the temp sensor working? b) use a freeze spray to cool it off so you can diagnose on your schedule instead of mother nature's. Freeze spray can be canned air held upside down, brake cleaner might even get it cold enough.

 

[Hay Dude]

I’m going to try a little more today. I have some help for a few hours. Then I gotta get back to making some money.

 

[Hay Dude]

It seems odd that only one function is failing if the ECU is bad. I’m more inclined to think that the ECU is not getting all the necessary inputs needed to determine that the glow plugs should cycle. Temp sensors are typically resistive inputs, they should have a linear change in resistive value over a specific temperature range. Sensor manufacturers typically offer a chart that lists proper resistance values for given temperatures. Does the service manual cover checking the temperature sensors for accuracy of the temperature inputs? Is there any kind of summary in the service manual that lists all the inputs into the glow plug cycling decision? Does the manual have any diagrams that detail the glow plug circuits? Or whether or not there is wiring connected in parallel that could monitor glow plug circuit integrity?

I like making things work as designed too. If I lived anywhere nearby I’d stop in and offer a hand. I’m sure there are others here that would be willing to help also. Not having a similar tractor or access to relevant manual sections does limit our usefulness though.

It may not be. And it is of concern to me.
The glow plug issue is ”old”. At least 2 years old and could be as much as 10.
A new issue, just a few month old, possibly related, is my small side display keeps blowing fuses. It’s frustrating because it digitally displays the tractors RPM. Great for PTO usage of round baler, rake, tedder, bush hogs.
It now blows a fuse quickly. Sometimes it takes a day, sometimes a second.
Related to GP issue? I don’t know.
Remember, “I’m only doing this for drama”, so don’t give it much thought.

 

[K5lwq]

It may not be. And it is of concern to me.
The glow plug issue is ”old”. At least 2 years old and could be as much as 10.
A new issue, just a few month old, possibly related, is my small side display keeps blowing fuses. It’s frustrating because it digitally displays the tractors RPM. Great for PTO usage of round baler, rake, tedder, bush hogs.
It now blows a fuse quickly. Sometimes it takes a day, sometimes a second.
Related to GP issue? I don’t know.
Remember, “I’m only doing this for drama”, so don’t give it much thought.

Hey maybe you could replace the fuse with a push button and another fuse. That way you can push the button take a reading and release before the fuse blows.