Transmission Calibration 2007 John Deere 3120

[OzGrasshopper]

Hi All, i've just relised that i put this post in wrong thread yesterday (getting bit old & forgetful ) i've had the above unit since new, at around 800hrs i started to find that tractor would on occasions only move at about 1/8 norm opp speed when pushing forward or reverse pedals. i could overcome this by cutting reves right down, drepressing pedal & building revs back to working level and all would rectify?. JD dealer found it was a "computer calibration issue" & reset on board computer unit & all seems fine. Question has anyother JD 3120 owner experienced this? cheers OG.

 

[beenthere]

Don't have that on mine, but glad to hear that you have yours fixed up and "calibrated".
:cool2:

 

[chickenman]

if it's anything like mine you can calibrate the controller by turning on the key and pressing each pedal all the way and holding it for at least 5 seconds, this tells the controller that it is at full travel.

turn the key off and on for each calibration.

do the throttle the same way, turn key on and move throttle to full for at least 5 seconds

the engine doesn't need to be running during the calibrations.

if the tractor moves forward and backward when the pedals are pressed , under no circumstances do an auto calibration which on mine requires you to move a fuse from a holding position to the controller calibration position.

and it helps to run the engine at the proper rpm's, 2000 or better on mine

i run mine at 2250 mostly

and it doesn't hurt to occasionally do a calibration of the pedals and throttle

 

[OzGrasshopper]

thanxs Chickenman - that is invaluable help to me - i didn't see that in the manual or did i miss it?.
while on that pedal speed issue, i've heard from another 3120 owner that there is a "2 stage" action on the forward pedal - ie u work with first section of depress, then put foot right down & it moves into a "transport" mode in the last section of pedal drepressing? mine has never done that, but i recon there was poor setting of calibration right from the start, as its a different "feel" to the tractor since recalibration.....do u have that 2 stage operation on the pedal?
- dont get me wrong, overall i really enjoy working this tractor - it has out performed my expectations:thumbsup:thanx u so much 4 ur help cheers OG

 

[chickenman]

thanxs Chickenman - that is invaluable help to me - i didn't see that in the manual or did i miss it?.
while on that pedal speed issue, i've heard from another 3120 owner that there is a "2 stage" action on the forward pedal - ie u work with first section of depress, then put foot right down & it moves into a "transport" mode in the last section of pedal drepressing? mine has never done that, but i recon there was poor setting of calibration right from the start, as its a different "feel" to the tractor since recalibration.....do u have that 2 stage operation on the pedal?
- dont get me wrong, overall i really enjoy working this tractor - it has out performed my expectations:thumbsup:thanx u so much 4 ur help cheers OG

i have just one rang for the pedals but a 3 range transmission

on mine the pedals and throttle rotate a potentiometer and that may slip or change values and without recalibrating them the controller has no way of knowing

so if you have this problem often, loose pots may be the cause or a loose connection

i'm just assuming that there wasn't a radical change from the 10 to 20 series

 

[OzGrasshopper]

yes mine has the same setup, 3 working ranges, pedal down forward or reverse - cant say i noticed any "2 stage" action on the pedals.
i was interested in ur opp revs - 2250 is exactly my choice engine sounds really comfortable there - i use mid range (marked B on selector marking) 90% of the time on the farm. real heavy slashing i go down to simply use slower ground speed. i use recommended 2500 for PTO on both low & mid range & slasher & all runs well at that.
cheers OG

 

[Cocre]

Hi All, i've just relised that i put this post in wrong thread yesterday (getting bit old & forgetful ) i've had the above unit since new, at around 800hrs i started to find that tractor would on occasions only move at about 1/8 norm opp speed when pushing forward or reverse pedals. i could overcome this by cutting reves right down, drepressing pedal & building revs back to working level and all would rectify?. JD dealer found it was a "computer calibration issue" & reset on board computer unit & all seems fine. Question has anyother JD 3120 owner experienced this? cheers OG.

You probably had a throttle position sensor issue. I had a similar problem last year. I suspect what the dealer did was calibrate the sensor. The throttle position sensor calibration on a 3x20 series is a bit more complex than chickenman describes, but easy enough. I really suggest you buy the technical manual for your model. It cost a few bucks but is well worth the price.

 

[chickenman]

also i learned to not use mfwd except when needed

 

[Cocre]

also i learned to not use mfwd except when needed

I use it all the time, except when I am on a hard surface such as concrete or asphalt. I guess when I am on my tractor I need it all the time. I'm pretty much using it to shove and pull things around.

 

[chickenman]

I use it all the time, except when I am on a hard surface such as concrete or asphalt. I guess when I am on my tractor I need it all the time. I'm pretty much using it to shove and pull things around.

it adds wear and tear on mine because there is no differential in the drive line between front and rear wheels so any tire wear puts a strain on the drive line also tight turns put a strain on it