S switch is stuck ON...only have 1st and 2nd

Hi!
I'm new here, so please be patient with me. I'm also new to Forums in general, so I have much to learn.

I have been helping my Mother-in-law get a few things squared away with her 90 Accord. She's almost 85 and needs a little help occasionally.

I took her car for a lube and oil job at our local Texaco XPress lube and when I got the car back, the S light on the instrument panel was on. I had NOT seen this before and to be honest, didn't even know what it was. Our 88 Accord doesn't have this feature.

I went back inside and reported my findings. The crew did everything I could ask to try and locate the reason, but no luck. I decided to take it to my mechanic. As I drove away, I realized I was starting out in 2nd gear even though I was in D4. I had to hold my speed down to keep the RPMs low as I limped to my mechanic's shop. I discovered along the way that I could shift to L and start out okay, but the rest of the gear selections are all 2nd gear.

My mechanic spent about 2 hours trying to isolate the problem, but no luck. He has set me up with a transmission specialist for next week, so I will eventually get to the bottom of this. I was wondering, in the meantime, if anyone here had any idea what has happened.

I should add that this car has had a history of shifter problems. It has been hung up in Park several times for me, but I have always managed to jiggle the lever just right and it would come on out. I suspect the kid at the lube place had the same problem and I'm guessing he accidentally hit the S button on the shifter. There have also been several occasions when it was difficult to get the key out of the ignition.

Any suggestions would be greatly appreciated. Thanks!

Steve