Also not in the gear indicator? (those blink when the transmission has e computer issue)
Anyway it could be:
- Bad connection
- Bad connection due to heat (stuff expanding) not likely
- Solenoid issue in the transmission (solenoid A and solenoid B come to mind)
- Control unit issue not seen by the CEL system unlikely but it can happen.
i'd do a base run down,
connections (e.g. A/T gear position switch, wire, connector
fluids (level, filter, strainer)
then go further with troubleshooting.
hydraulic system,
- shift valve
- linear solenoid
- pressure regulation