John Deere 629.31: Control Unit Internal Fault
Issue description
The microprocessor inside the module has detected an internal error, memory failure, or software configuration issue. The system's reaction is typically limited or no functionality from the affected module.
Applies to these machines
33 machines- 6110M
- 6120M
- 6130M
- 6145M
- 6155M
- 6175M
- 6195M
- 6110R
- 6120R
- 6130R
- 6145R
- 6155R
- 6175R
- 6195R
- 6215R
- 5085E
- 5090E
- 5090EL
- 5100E
- 5085M
- 5095M
- 5095MH
- 5105M
- 8245R to 8400R
- 9470RT
- 9520RT
- 9570RT
- 9570 STS
- 9670 STS
- 9770 STS
- 9870 STS
- 204L
- 304L
Check the cause
Restart the machine by cycling the key to the OFF position, waiting, and restarting to allow the module to re-initialize
Check for accompanying codes, such as CAN bus faults (e.g., 000639.xx) or voltage codes, which could indicate a severe voltage spike or grounding issue
Verify the module prefix (e.g., ECU, TCU, CCU, XSA, HCU) on the display to identify exactly which module is failing
Repair steps
Turn off the tractor and remove the key.
Turn off the tractor and remove the key.
Inspect the wiring harness and ground connections.
Inspect the wiring harness and ground connections leading to the suspect module (identified by the prefix) to rule out external electrical shorts causing module erratic behavior.
Restart the tractor.
Restart the tractor.
Check if the code clears.
If the 000629.31 code clears and does not return, it was a transient software glitch.
Determine if the module has failed.
If the code remains active (Condition Exists), the module has suffered a hard internal hardware or flash memory failure.
Remove and replace the specific module.
Field repair of the internal microprocessor is not possible. The specific module must be removed and replaced.
Install the new module and have it programmed.
Install the new module. Note: A replacement module will require a John Deere dealer to flash the correct software payload and calibrate it to the tractor using Service ADVISOR.
Parts you might need
(1)Engine Control Unit (ECU), Transmission Control Unit (TCU), or Chassis Control Unit (CCU)
Must order based on prefix and serial number. Modules are generally shipped blank or with base software and must be programmed by an authorized John Deere dealer to match the machine's specific configuration.
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