JD 3320 will not move after calibrating throttle sensor

[Nosille]

I recently purchased a JD3320. It was showing a few error codes when I bought it but operated fine, so I talked the guy down a little and brought the tractor home. Upon getting it home, I started tracking down the codes. For code 08 the users manual said to check the throttle sensor, and upon inspection I found that the sensor bracket was bent and no longer engaging the throttle. A little finessing with a hammer got it back in place, and a little time with a voltage gage got the idle readings back where it should be, ~0.790 volts. While searching this site for the proper voltage, I ran across a calibration procedure that I decided to try as well. Everything seemed to have gone well. Tractor cranked right up with no error codes. However, when I went to get it out of the shop the hydro would not engage. I know it has to have something to do with the calibration, but I have repeated it multiple times on the throttle and both hydro pedals with no success. Any ideas?

 

[sd455dan]

Well IF that is a basic Throttle position sensor , most vehicles computers send a regulated +5 volts to the TPS which is a variable resistor.
When you hammered the mount into place it may have damaged part of the resistor which sends back a portion of the voltage depending on the throttles position .
I would ground one side of a volt meter and then check that with a key on
that the return wire from the sensor is varying from the .7volt or so at idle position thru about 4.5 to 5 volts wide open... obviously the engine is not running during testing.

Is there a neutral position and if so does the throttle (engine speed respond normally)?

If this is not a TPS then what i posted is probably useless

 

[Cocre]

Turn off LoadMatch, see if that helps. I had issues once with LoadMatch (no errors) and re-calibrating the TPS resolved the issue. It seemed to be the only symptom of an out-of-range TPS. If the TPS is way bad perhaps Loadmatch would keep the tractor from moving at all.

 

[Nosille]

Well IF that is a basic Throttle position sensor , most vehicles computers send a regulated +5 volts to the TPS which is a variable resistor.
When you hammered the mount into place it may have damaged part of the resistor which sends back a portion of the voltage depending on the throttles position .
I would ground one side of a volt meter and then check that with a key on
that the return wire from the sensor is varying from the .7volt or so at idle position thru about 4.5 to 5 volts wide open... obviously the engine is not running during testing.

Is there a neutral position and if so does the throttle (engine speed respond normally)?

If this is not a TPS then what i posted is probably useless

I hammered out the bracket after removing the sensor. The sensor reads ~0.790 volts at min throttle and around ~2.9 at full throttle. Engine revs fine.

 

[Nosille]

My service manual arrived today, and after studying it, I decided to go through a full hydro calibration. After some initial difficulties with the petals reading high at full travel, I managed to get most of the way through the calibration. However, I keep getting an error during the forward coil calibration.

The calibration always proceeds like it is going to work. The tires start slowly, but gradually pick up speed. They work their way up to a pretty good speed, but then stop suddenly with a flashing error message. Has anyone else experienced this problem? Any trouble shooting suggestions? Would the MFWD speed sensor be a factor? I am prettying sure my MFWD sensor is out.

I assume I am stuck needing to complete a full calibration now. I really need to get the tractor usable again. I can't believe what started as a simple attempt to fix a bent bracket has devolved into an unusable tractor.

 

[Coyote machine]

Starting at your beginning point, the tractor was able to run and move BEFORE you touched the bent bracket, yes?
Did the bracket look like it might have been bent on purpose? If so it would seem logical the prior owner knew something was wrong, and might have disabled the sensor by bending the bracket?
You said there were a bunch of error codes present when you bought it, right?
What if you were to disable the TPS again just to see what happens?
You can fix it later if you can get to use it now, right? It may be beyond a calibration, and need further troubleshooting of codes before you can actually fix it to specs.

I'm not familiar with the MFWD, and something you said was 'out', do you mean out of spec/range/calibration?
Forward coil too, needing adjustment?

My sense of it is you've adjusted a lot of items and going back to square 1 may be your best approach at this juncture; after all, unless someone already did all you're doing and messed it all up it wouldn't likely have run and moved for you originally....

 

[arlen4720]

what are the specific error codes?

 

[Nosille]

Yes the tractor would drive before I touched the bent bracket. I have thought the same thing about the bracket being bent on purpose, and I did try bending it back for a short while after this whole thing started. However, at this point I cannot see how a bent bracket will help me. All that would do is make the computer think the tractor is always at idle. I assume some previous mechanic could have gone through a process where he moved the sensor by hand at critical points in the calibration process to get a desired result, but I do not know what it would be.

I would love to go back to square one, but now that the computer has tried to calibration, I do not think it is possible.

 

[Nosille]

what are the specific error codes?

The original error codes were 06 and 08. However, I do not have any standing error messages right now. The first time I turn the key on after a failed calibration, it flashes 04 and 06 once and then clears.

 

[arlen4720]

The original error codes were 06 and 08. However, I do not have any standing error messages right now. The first time I turn the key on after a failed calibration, it flashes 04 and 06 once and then clears.

So 4, 6, and 8. Engine speed, MFWD Speed, and Thottle position. I'm thinking the calibration failed becuase you tried to calibrate without a working MFWD speed sensor (ERR_06). The tractor will still work at a degraded level without the throtttle position and MFWD speed sensors, but maybe really went to pot when you tried to calibrate.
Your symptoms during calibration fits....It spins the wheels for a time, then, when it doesn't detect wheel movement, throws an error and aborts.
I think I would look over the wires to that sensor closely. Maybe replace it and try again.

 

[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.