Hey guys! I recently acquired a very clean 2 owner 1992 SC400 with 129k Miles in dark blue and everything works amazing except 1 major thing besides the notorious hood shock and trunk shocks.

in Drive it is stuck in 3rd gear.
I have been driving it going from L to 2 to D and it’s been working but it is super annoying

recently had the solenoids pulled out and tested and work great , had the screens cleaned , new transmission filter , checked the fluid and topped off and unplugged the battery to have the car do a full reset and same issue!

has anybody come across this and fixed it?

 

Sounds like the ECU. If you can force the transmission to use it's gears but in D it only wants to use third sounds like a control unit issue, and the ECU controls the transmission. Also sounds like something an ECU with leaked caps would do, mine would not go into overdrive with it's bad ECU. Pull the cover off and look for corrosion.

 

so if that is the issue , is there a fix besides swapping the ECU?

 

I will agree with replacing/repairing the ECU. I have heard good things about TaninAuto, they are currently charging about $200 to repair the capacitors. I did not have the same issue as you, my transmission would not shift into overdrive, but if the solenoids were the not the issue, I would look into the ECU. First, I would first open up the ECU and see if there is any leaking capacitors, then go from there. These cars are notorious for their leaking capacitors, it is a good preventative measure to keep your SC running pristine.