md90

90 Accord LX, auto, 191,000 mi. driven responsibly....most of the time

I had been using non-Honda tranny fluid for the last few years with no problems. About two months ago, I started experiencing rough shifts, a blinking "S" light on the dash, and an occasional hesitation on starting (like it was having trouble shifting into first gear). The tranny fluid was changed twice with Honda ATF and the problems disappeared. The car shifted perfect for the last two months. Although I could feel a slight vibration at different points as engine speed increased.

Thought everything was alright until today. I started the car and before I could even shift out of park, the "S" light started blinking and the shift-lock solenoid began engaging/disengaging with each light flash. There was also a relay clicking sound coming from the tranny control module area while this was happening. I still feel a vibration at certain points throughout the RPM range when accelerating.

Anyone ever have something like this happen? Could this be the last days of the tranny or simply a bad control module? Any help greatly appreciated.

Nightshade

My guess would be t have the shift lock solenoid checked out (I think thats the name...the relay thing that tells it the brakes are on to shift to gear). I am pretty sure that will cure your locked shifter problem (not 100% though).

As for the tranny vibrating and the blinking "S".....the S on your dash means you are in "Sport " mode..in otherwords overdrive is disengaged. These indicator lights do this a lot but it may also mean your tranny is being put in and out of overdrive mode a lot. Not exactly horrible but get it looked at.

The vibrations could be several things...

Check the alignment....it can cause some weird feeling in the car
Also check the axles while your there (preventative)

Possible torqque convertor issue (they get old and wear out...20 year+ old cars are old and worn).

md90

Thanks for the ideas. The shifter is hard to move from park but that is due to a sticking shift cable. Once it moves from park, it moves freely from reverse to D2. The solenoid seems fine. Today on the way home from work the "S" light blinked intermittently and the tranny would shift from 4th to 3rd and stay there. It would only go back into 4th after stopping at a light and starting again. I went out tonight to see if I could get a code from the TCM/ECU. This is what it spit out:

Check Engine light = code 15
"S" shift light for tranny = code 12 or 21 (depending on which you look at it)

Does anyone know the tranny controller codes for a 90 LX auto? I checked my books but could only find standard ECU codes such as 15 = ignition output signal.