Transmission/trans-axle

This is a code for the transmission selector switch which sounds like it has gone bad, here is a guide and some diagrams (below) of how to get the problem fixed.

https://www.2carpros.com/articles/how-a-neutral-safety-switch-works

and

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

Here is the wiring diagram and how to change it, that's what I would do.

Please check it out and get back to me.

Cheers, Ken