Immediately press the pedal all the way down and release.
If you are intentionally in this mode to find other codes, you can navigate using the machine's controls: How to retrieve codes on a John Deere 6420, 6000 series john deere d1a code
On many models (like the 6000 or 7000 series), there is a specific slot in the fuse box for diagnostics. If a fuse is in this slot, the tractor defaults to "d1A" mode and may not move. Immediately press the pedal all the way down and release
If your tractor is stuck in this mode and won't move (often disabling the forward/reverse lever), it usually means a diagnostic fuse was accidentally inserted or a wiring short is tricking the system into "thinking" it should be in diagnostic mode. Common Causes for d1A Appearing Unexpectedly If your tractor is stuck in this mode
Look at your machine’s fuse diagram. Find the slot labeled or "Diagnostics" . Action: If there is a fuse in that slot, remove it .
Corroded terminals or a short in the diagnostic wiring can trigger the mode. A known John Deere service solution (DTAC #71449) addresses tractors entering this mode on their own due to grounding issues.