My 1990 accord started having issues going into 2nd gear, then stopped going into it altogether (still works manually, just not in drive). Then after changing the lower shift solinoid and fluid it lost 1st gear entirely, not even manually. Then i put a new tcu into it when it was only sending 3v and that didn't fix it either. I also ran new wires from the tcu to the solinoid. The only other possible issue I could see is that my transmission dosent like the dexron IV i put in it.

What is going on with my car

the sport mode light is flashing. And the tcu is giving me codes 7 and 8

I'm only reading 3-4v at the solinoid at idle

 

I don't have the wiring diagram on me, but look to see how the tcu is wired to the solenoid in a factory shop manual. There are some free versions on the web that can help.

Was any work done on your car before you noticed shifting problems?

 

I actually figured out my issue this morning, my connector from the wiring harness to the solinoid was corroded in such a way that continuity still was there but had tons of resistance not allowing either solinoid to function.