I recently purchased a 2004 John Deere 672ch and when I shift into eighth gear it acts like it's in neutral. Anyone had an issue like this? What could be some cause? 1st through seventh work fine.
Welcome to HEF 672ch . Machine serial # ?
Machine numberDW672CH594204
The machine is a Series II . When roading , what gear does the console monitor show when the shifter is in 8th gear forward ?
Great question. Let me check that this weekend and I will let you know. Thank you for your help.
Just an FYI, the only code is an F412.
Engine diagnostic trouble code F412—Throttle Position Sensor Voltage Too Low.
Ok, took it down the road and when I shift into eighth gear the console does say 8th gear. It tops out at 1800 rpm, is that where it is governed? Could the TPS low voltage cause this? When I let off the throttle in 8th gear it does act like it is in 8th gear and not freewheeling.
So, TPS voltage too low...bad TPS?
I highly doubt the TPS low voltage would cause the no/poor 8th gear issue. I would test the continuity of gear position switch terminals in the transmission control module. See (3) test procedure screenshots below. If control module checks out I think a full transmission pressure test would be next. .
Thank you for the info, I will check this out.
One last question, where is that located, behind the seat?
It’s just below the gear shift lever plate . See screenshot below from parts site. .
Yeah, I found it. Thank you for everything. I will follow up with my findings.
Here is the update. Had a mobile mechanic come and help. He has worked for Empire and RDO. We replaced the TPS. The F412 code is still there. I can only get a max rpm of 1900 out of it. It should be about 2300. Going to adjust throttle linkage. Still no eighth gear. Replaced the Y11 solenoid, changed trans fluid, filter and cleaned the strainer. Calibrated the system after all this work. I am told that there is 24v to that solenoid but have not confirmed it myself. It feels to me like it is an electrical issue oppose to bad clutches. Just my thought.
There were no issues getting the transmission to pass calibration ?
Not that I know of, the tech did not say that there were any issues.
I think I'm going to have my local RDO double check things.
I have my local RDO Deere dealer coming Friday, the 24th.
Final update. I had my local RDO come out and they found the transmission filter head bypassing fluid because the check valve in the head was weak. Replaced the head and all is well. Thank you for all of the info and expertise.
@672ch , thanks for following up !