First off I have checked several Honda forums and read many..many pages of problems with VSS, TCU, shift solenoids, TPS and coolant sensors being possible causes.
My daughter has a 92 Accord LX sedan with shifting problems, I will list the problems and the solutions i've tried to get the car going. When we bought the car the speedometer was not working but everything else was fine. Replaced the VSS and noticed it had already been replaced just recently, my replacement also did not fix the speedo problem. She drove the car for a week and started having problems with the tranny not upshifting thru forward gears with only reverse working and D4 light coming on (the D4 light DOES NOT flash, stays on bright or slowly dims and brightens back up and not in a steady fashion). Tried pulling codes through the service plug and no codes come up.
I have removed the shift solenoids, applied 12v's and cleaned them, checked voltage at the terminals that the solenoids plug into and voltage was correct.
Drained and refilled trans fluid.
Including the original TCU, I have tried 3, first one I bought did not work at all, opened it up and had a burned R41 resistor, sent it back and got another, visualy looked fine, put it in and car had same problems as with the original TCU. I replaced all the capacitors in both TCU's, all resistor's ohm'd correctly and this did help some, before capacitor replacement I could only drive the car about a 1/4 mile and would have to pull battery cable to reset it to get home. After capacitor replacement ( in both TCU's) I drove car for 5 miles and only lost D3 and D4.
I have replaced the TPS and adjusted it in different positions, only thing that seemed to help was the idle somewhat, car does have 206,000 miles,
I checked the cable from the throttle body to transmission and it is not sloppy, put very slight pressure on cable and lever at transmission starts to move.
After cleaning the shift solenoids I have noticed that when I put into reverse there is a few seconds of nothing then the sound of like bad syncronizers in a manual transmission then it slams into gear (this only happens shifting into reverse) doesnt do it all the time.
I am at my wits end and keep falling back that maybe one of the shift solenoids are bad or there is a problem somewhere with VSS. I hate buying used parts but the solenoids are $125 ea. my cost, I work at a parts store (CARQUEST) and have for 29 years and have been the automotive field for 33 years.
Any more ideas would be greatly appreciated!!!!

 

I did remove the VSS and made sure the drive pin was spinning and it does. I suppose the cluster is bad causing the speedometer not to work. Could this also cause problems with the transmission?

 

No, a bad cluster won't cause a problem shifting.

Have you checked the transmission fluid level? Have you changed the transmission fluid?

When you checked for codes, did the check engine light stay turned on? Or did it flash codes too?

Have you tried checking for D4 codes again, since changing the TCUs?

 

Fluid level was fine but I went ahead and changed it and refilled.

The check engine light just stays on, does not flash any codes.

Checking for D4 codes, is this done through the same blue service connector under the right hand corner of dash/kick panel?

 

Yes, you check D4 codes the same way as CEL codes.

 

As PA said - check for codes and let us know what if any you have.

A few things come to mind - I would re-check the "cap's" to see if they are blown again.....a poor connection at the shift solenoid(s) can and will cause high resistance and blow the "cap's" repeatedly.

 

Ok, I'll recheck the caps in both TCU's and try pulling codes again.
Which solenoid pack usually causes the problem, shift or lockup?

 

The lower - shift - one. But it won't hurt to check both for dirt and corrosion in the connectors. If the connectors look bad and or if the caps are blown again I'd go ahead and get a two wire waterproof pigtail connector and replace them......use a good crimp and heat shrink on the wires.

I looked on "link" today

 

Ok, finally got to mess with it some. I rechecked the capacitors in both TCU's and they looked fine, I went ahead and ordered a reman TCU and took the car for a test drive and all seemed fine. Drove it about 3 miles then it started disengaging out of D4 off and on and the same if I downshifted to D3. If I started from a stop and upshifted from 1st all was fine. No D4 light anymore and still no codes. The reman TCU seemed to help but did not fix it so the Accord tranny hammer has put another nail in my coffin!!

 

Really sounds like an issue with the solenoids. Here is a link with some info that might help - Honda Electronic Transmission Problem- Troubleshoot, Inspection, Repair, Replace.

If you have to replace one of them....I personally would get one or two from a bine yard and go from there......$125 is too much IMO.