S3 light flashes

well i just bought this car a week ago its a 91 integra ls at. and the day after i bought it the s3 light started flashing on the freeway while in D there was no differnce and anything the car ran fine and shiffted through all 4 gears fine. yesterday it came on again but this time i put it into S when the light started flashing. but now while in S it wont shift into 4th but in drive it shifts to all 4. only while in S does it not go to 4th. i checked to see if i was throwing a code and its throwing a code 9. can anybody tell me where the #1 top dead center sensor is? also should i be worried? also what does that sensor have to do with the transmission? also i noticed that the light only turns on after driving for while could it be that the trans is overheating? also the light resets with turning the car off and on. anybody have any idea? i already bought a haynes book but it doesnt say anything about the s3 light

HELP my car is sick :sick:

You need to search a bit sir. I’m nice today, so here ya go.


Check yer ECU for codes, it should be blinking.

EDIT: you did check them, it’s a start.

most likely your lockup & shift solenoids. there’s a TCM box under the dash in the back on the left side with a LED that flashes codes. put the key in the ii position i think, the one just before the last and count the flashes for your trouble codes. long flash indicates a donomination of 10 and short flashes are singles. ie, long, long, short, short, short = 23