OK..check that off the basic list.

yes...sure....faulty TCU signals can effect shift valve control......maybe even a bad ground...try something simple like unplugging unit and reconnecting....it's under driver seat....

do you have fault P1884? seems a common one with TCU issues....

anything else not working? any other codes? have you done any repairs lately or changed/replaced anything else? any BCU reconfiguring? changed a battery? shorted something? Fuses out?

and has the trans fluid been changed or level checked?

 

I'll disconnect and reconnect it...
No fault codes recorded..
Transmission oil and filter changed after this symptoms appeared.
No I've not replaced any parts or shorted any wires,,

 

possible that during trans fluid change the harness to XYZ got damaged? Or fluid level not correct.....has to be filled when running...