I have a 2007 S-Type 3.0L automatic with 105K miles. Last week we had lots of rain and the sunroof was vented so water leaked in on top of the gear shifter. Upon starting the car the lights on the shift box would flicker and I could not get the car out of reverse. Finally, after a few seconds it released and drove fine.

I parked the car for a few hours and went to drive it again and all hell broke loose on the dashboard. Lights and warnings of all kinds were going off so I drove it back home, still it drove fine. I assumed my alternator was bad so I let the car sit a week until I could replace it.

Today I tested the alternator and it is fine. The car now has only the amber transmission light steady illuminated. The lights on the shifter were steady lit and the shifted out of park freely. I test drove the car and it shifts just fine but the transmission light still is on. Any thoughts?

 

Some dubious wire/connector or a flattish battery.

You could read the codes in case they help.

If it's an autobox, check the 2 bolts at the trans side that hold the shift cable are there and not loose.