Hi, been lurking off and on and just bought a new to me 90 Accord coupe. I got a deal after the previous owner spent quite a bit in new parts only to develop the usual no shift or manually shift only issue and had a "reputable" tranny shop quote $3000 to rebuild it. They chose to put a known good used tranny in it only to find it didnt solve the issue.
Anyway, I replaced the tcu and almost everything seems good. Still shifts a little harsh, mainly if I let off the gas and it kicks up to D3 or 4. Have replaced both solenoid packs with units that click and seem to test good as the ones on it sounded weak although have gotten better after cleaning. It made an improvement.
Problem is my sport button doesnt seem to do anything. The light does not illuminate when pushed, does on start up as it should so I know the bulb works.

I cant seem to find info on where the wiring goes from the shifter to confirm its still plugged in as I suspect it could be possible that someone tried disconnecting it when the tcu was bad and the S light was on constantly.
My other thought was maybe the tcu I installed isnt compatible or has an issue on the sport circuit. Is this possible?

Sorry for the long post.
Oh and I dont get any trouble codes.

 

So to update, my suspicions were correct, someone tried fixing or disconnecting sport mode. The button had been apart and put back together without a spring and the contact put in the wrong slot.
So with some creative thinking and a little Macgyver work (there's one to confuse the young ones on here) Haha! It works now.
Now to figure out if the somewhat harsh shift is due to the wrong fluid being used or something else.

 

Verify the battery is fully charged, holds a charge and that the battery terminal connections are clean and tight.

Verify engine/trans/harness grounds are clean and tight.

Verify your throttle cables are correctly adjusted. Pedal to TB should have no slop nor tension, and TB to trans cable should also have no slop nor tension.

Verify there are no engine/ignition issues. If the engine is out of tune it can cause the transmission to feel as though it shifts hard. Check cap/rotor/spark plugs/wires.

Check your wiring harness between the NM/NC sensors on the right side cover back to the TCU. Pull NM/NC sensors, if they are covered in slurry this can affect shift quality, usually related to erratic overly harsh shifts.

Warm up the engine, charge every gear circuit P-R-N-D4-D3-D2-D1>P(leave engine running), pull dipstick, wipe clean, reinsert fully, pull out and check level. Should be within hash marks of dipstick.

 

I thought I read on a tech thing somewhere that there was some slack in the throttle cable?
I'll double check it then.
I think it has a little on the trans side.

 

No slack, as the throttle blade begins to open so should the lever begin to raise. A quick adjustment is to verify the TB is closed, loosen the locknuts, push down on the trans throttle lever with your finger, remove slack from cable, and then tighten lock nuts. There is a 2mm adjustment allowed, but an overly tightened/loosened cable will cause incorrect shifting.