JD 3320 will not move after calibrating throttle sensor

[Nosille]

Thanks arlen4720.

I came to the same conclusion and ordered a new MFWD sensor this morning. It should be in tomorrow. I will install it this weekend, and let ya'll know how it turns out.

I am glad someone else had the same idea. I was not very confident in my decision, but couldn't think of anything else to try and figured I would eventually have to buy a MFWD sensor anyway.

 

[arlen4720]

Thanks arlen4720.

I came to the same conclusion and ordered a new MFWD sensor this morning. It should be in tomorrow. I will install it this weekend, and let ya'll know how it turns out.

I am glad someone else had the same idea. I was not very confident in my decision, but couldn't think of anything else to try and figured I would eventually have to buy a MFWD sensor anyway.

I think you are on the right track, but just go the extra mile in scrutinizing the cabling and connectors for the sensors also. There have been a few threads here and other forums of those cables getting pulled loose from catching a stick or something of that nature.

 

[Nosille]

The sensor pigtail is visibly damaged at the sensor. It looks like something caught it and nearly pull it out of the transmission. So, I have good justification for replacing the sensor. However, I will take another look at the rest of the cabling for problems when I replace it.

 

[Coyote machine]

The sensor pigtail is visibly damaged at the sensor. It looks like something caught it and nearly pull it out of the transmission. So, I have good justification for replacing the sensor. However, I will take another look at the rest of the cabling for problems when I replace it.

The above could explain why you're having a difficult time trying to calibrate. Look carefully at the wiring at that connector to see if any of the wires were stretched or torn inside the harness a ways downstream of the cable strain. Mutistrand wiring is not very strong and yanking or pulling on it can break strands inside the cable which will only be evident by inspecting the wiring under the sheathing.

 

[Nosille]

I have good news to report. Everything is working and I was able to drive the tractor out of the shop and around the neighborhood! Thanks to all that provided advice.

The replacement MFWD speed sensor was the missing link in my calibration. This time, instead of the wheels continuing to turn faster and faster, the computer registered a successful calibration as soon as the wheels turned a perceivable amount. All the calibration is apparently looking for is the threshold voltage required to start the wheels moving.

 

[arlen4720]

I have good news to report. Everything is working and I was able to drive the tractor out of the shop and around the neighborhood! Thanks to all that provided advice.

The replacement MFWD speed sensor was the missing link in my calibration. This time, instead of the wheels continue to turn faster and faster, the computer registered a successful calibration as soon as the wheels turned an almost unperceivable amount. The calibration apparently uses the speed sensor to determine the threshold voltage required to start the wheels moving.

That's great news. Are you error code free now?

 

[Coyote machine]

Good work! Nice outcome. So how was the tractor running before you fixed the problem?

 

[Nosille]

I am error code free.

The tractor ran fine before as long as I was easing around in low gear. I did note it holding back in high gear like load match was kicking in.

I took it for a drive yesterday and it felt much better. At full throttle in high gear the speedo read 15 mph at full pedal. I didn't have a speedo before, but I would estimate that it would barely break 10 mph before the repairs.

 

[Nosille]

For anyone with similar problems these are the lessons I learned from my ordeal.

1. Disconnecting any of the big three sensors (throttle, forward pedal, reverse pedal) with the key on will force a recalibration of all three sensors. Don't do it unless you are sure all three will test out to factor specs.
2. There are two calibration options: A) a quick single sensor calibration that must be repeated for all three sensors and B) a full computer reset like calibration that includes the forward and reverse proportioning solenoids. Do not choose option B unless you are sure all sensors and hydraulic controls on the tractor will test out to factor specs.
3. If any of the sensors/solenoids included in the calibration does not fall within factor specifications, at both travel extremes, the calibration will not be successful. The quick calibration will provide no indication this is what happened, but the tractor will not operate afterwards. The only indication with the full calibration is that it will refuse to move on to the next step. In my case the rest position on the reverse pedal was good but max travel was not, so the display continued to read rpedal no matter how long I held the pedal or how many times I cycled it. I ended up taping a stack of washers to the pedal stop to get the high reading under the required threshold.

 

[Nosille]

That brings up another question. What is the proper way to adjust the pedal sensors?

I set the low values by loosening the bolts and moving the sensors. However, the only way I could find to control the high value was by reducing the pedal travel. As a temporary fix, I ended up taping washers between the floorboard and the physical stop on the pedal. I am considering replacing these washers with a piece of dense foam that has been glued to the bottom of the wedge shaped petal stop, but there has to be a more official solution.