I have just acquired a 1992 accord lx 156K miles. The car was not driven for 6+ months. Other than probably needing a CV joint, the first 50 miles after purchase were without issue ( the tranny actually shifted very firmly!) Now the D4 indicator stays on and the transmission appears to not be shifting. Manually operating the shift lever seems to result in two gears changes only.
Initially removing the negative lead of the battery would turn the light off until the transmission was put into gear, then D4 would illuminate (no flashing). Shorting the diagnostic connector only resulted in the check engine illuminating. No flashing lights period.
The tranny fluid was drained and replaced. The negative battery lead removed and replaced. The car started and transmission lever exercised. D4 illuminated again. Further attempts at clearing the fault (removing the negative battery terminal or removing the ECU fuse) have not been able to clear the D4 indicator.
At this point I am not sure where to start? any suggestions would be greatly appreciated.

 

FYI...
While disappointed that I rx no replies I do appreciate the information that i was able to obtain from other posts.

I disconnected the battery, pulled the TCU, replace two smoked resistors and an electrolytic cap. Reconnected the battery... started the car... D4 cleared and the car is back to running great and shifting great!!!

It is quite possible that the damaged components were the result of some other failing component... for now I am simply going to cross my fingers ( and a keep a few extra resistors and caps handy)