First off, let me start by saying, I am by no means a heavy equipment mechanic. But I am fairly mechanically inclined and typically am capable of figuring things out/fixing them myself if I mess with it enough 
This will be lengthy but i’m trying to give everything i know and have done thus far. Any help is greatly appreciated. So, let’s get into it.
John Deere 450J: SN: 1TO450JXKCD218918
1 Active Code: TCU 523108.14
17 Stored Codes: 908.12, 907.12, 97.3, 1638.3, 523577.9, 523578.9, 522444.4, 2661.4, 2660.4, 522448.5, 522450.6, 522449.5, 96.3, 157.17, 91.9, 522447.6, 522447.5 (I know holy sh*t)
This dozer is a buddies. It has pulled left and had speed sensor codes for a while to my knowledge. I am not entirely sure the exact length of time but it has been ran that way for quite some time. A friend of ours (JD mechanic at the time worked on the dozer several years back and i believe did a null adjustment on it and got it tracking pretty good and straight but it still had a slight left hand pull. Probably had 2-300 hours put on it then it sat for almost a year and was not ran. I bought a piece of property and have borrowed the dozer and used it for several hours as well with it pulling left just mainly cleaning up brush and small trees. No heavy pushing or abuse. The dozer sat for 3-4 months throughout the winter and was essentially untouched. Come spring this year i began working on the property again. Dozer fired right up and i put it to work. I probably had 2 hours on it when the current issue occurred. As i was tracking back for another push of dirt the dozer locked the right hand track and on its own threw full power to the Left track. Took off spinning right. No matter the position of the drive joystick it sends juice to the left track only. It should also be noted that upon start up if you do not throw the park brake lever down that the dozer will stall out because the pump is loading up trying to send fluid to the left track.
I called that same friend (unfortunately he no longer works at deere, but he does now run his own service truck and has access to John Deere service advisor with all the manuals) he inspected the machine and narrowed it down to the PCP. You could unplug PCP and machine would idle just fine. As soon as you plugged in PCP machine would die unless you immediately threw the park lever down so that the left track was free to spin. 1550 dollars later machine has a new PCP… No dice. Didn’t fix it. Didn’t change a thing matter of fact. I can tell my friend that’s worked on it a few times really is not interested in messing with this thing. Nor does he have quite the access to parts that he used to at deere where he could swap say a new TCU on to see if that fixed issue or not. I myself located the speed sensors at back of machine and managed to get enough slack in harness that i could plug left to right and right to left. Same issue. Left track still wanting to spin on its own with right track locked tight. That leads me to believe that something internally on the pump must be stuck. Prefer not to have to call a John Deere service tech out but it’s looking like that may be what has to happen. Any tips and advice is much appreciated. I’ll also add this machine is an open cab and has spent likely its entire life but definitely last 6-7 years outside in the elements. The TCU doesn’t look the greatest but the connectors are clean and corrosion free.
This will be lengthy but i’m trying to give everything i know and have done thus far. Any help is greatly appreciated. So, let’s get into it. John Deere 450J: SN: 1TO450JXKCD218918
1 Active Code: TCU 523108.14
17 Stored Codes: 908.12, 907.12, 97.3, 1638.3, 523577.9, 523578.9, 522444.4, 2661.4, 2660.4, 522448.5, 522450.6, 522449.5, 96.3, 157.17, 91.9, 522447.6, 522447.5 (I know holy sh*t)
This dozer is a buddies. It has pulled left and had speed sensor codes for a while to my knowledge. I am not entirely sure the exact length of time but it has been ran that way for quite some time. A friend of ours (JD mechanic at the time worked on the dozer several years back and i believe did a null adjustment on it and got it tracking pretty good and straight but it still had a slight left hand pull. Probably had 2-300 hours put on it then it sat for almost a year and was not ran. I bought a piece of property and have borrowed the dozer and used it for several hours as well with it pulling left just mainly cleaning up brush and small trees. No heavy pushing or abuse. The dozer sat for 3-4 months throughout the winter and was essentially untouched. Come spring this year i began working on the property again. Dozer fired right up and i put it to work. I probably had 2 hours on it when the current issue occurred. As i was tracking back for another push of dirt the dozer locked the right hand track and on its own threw full power to the Left track. Took off spinning right. No matter the position of the drive joystick it sends juice to the left track only. It should also be noted that upon start up if you do not throw the park brake lever down that the dozer will stall out because the pump is loading up trying to send fluid to the left track.
I called that same friend (unfortunately he no longer works at deere, but he does now run his own service truck and has access to John Deere service advisor with all the manuals) he inspected the machine and narrowed it down to the PCP. You could unplug PCP and machine would idle just fine. As soon as you plugged in PCP machine would die unless you immediately threw the park lever down so that the left track was free to spin. 1550 dollars later machine has a new PCP… No dice. Didn’t fix it. Didn’t change a thing matter of fact. I can tell my friend that’s worked on it a few times really is not interested in messing with this thing. Nor does he have quite the access to parts that he used to at deere where he could swap say a new TCU on to see if that fixed issue or not. I myself located the speed sensors at back of machine and managed to get enough slack in harness that i could plug left to right and right to left. Same issue. Left track still wanting to spin on its own with right track locked tight. That leads me to believe that something internally on the pump must be stuck. Prefer not to have to call a John Deere service tech out but it’s looking like that may be what has to happen. Any tips and advice is much appreciated. I’ll also add this machine is an open cab and has spent likely its entire life but definitely last 6-7 years outside in the elements. The TCU doesn’t look the greatest but the connectors are clean and corrosion free.
