Hey All, I have a John Deere 850C Serial number T0850CX931376, it has a display fault F652 every time the parking brake is released, we installed a JD reman TCU Which did change things, we also changed pump speed sensor and right drive motor speed sensor. now I can get through the first part of the transmission calibration but as soon as I go into the track speed portion of the calibration, I get a 6L fault and cannot continue. I have access to service advisor, but between that and google I find absolutely zero information on either of these faults. Wiring has been checked out, in still trying to find out if the reman TCU needs to be programmed or not, some people say it needs to be others say it should be programmed from John Deere. Any advice or experience would be greatly appreciated.
Welcome to HEF HHREPAIR ! Did it have this code before the TCU replacement? The TCU should have come pre-programmed, but does need to be calibrated. F652 is for the Transmission Speed Control Switch. That will need to be addressed first. If you have Circus (sorry, Service) Advisor follow the troubleshooting procedure for that code. For step #2, you can backprobe instead of using the special harness.
Thank you for the welcome, I'm always looking for a good group of people to get advice from. The F652 was present, before and after the TCU was swapped. I have been trying to complete the calibration, and it will not finish. I have access to service advisor offline, but I have not been able to locate the troubleshooting steps for fault F652, I am new to Service advisor, so there is a good possibility I'm not looking in the correct spot. I will try pull it back up again, but if you have input on where I can find the troubleshooting procedure, I would appreciate it.
In the Operation and Test manual TM1588, section 9015 Electrical, sub section 15 Sub-System Diagnostics, then look for Transmission Controller Service Codes Diagnostic Procedures. It will be about half way down the list.
Hey, I wanted to write a reply and update this thread. First off, I appreciate the advice, I was able to find the troubleshooting procedure, and it led me right to the speed selector thumb switch on the joystick. I tested it and spec was 3.5v or less and it tested at 3.7 volts. I replaced it and all functions returned with no issues. Thank you again.