93 Sc400 Tranny Won't Go

[rekit]

93 SC400, 135,000 miles. When I first start it, it makes a fairly loud whirring sound from the trans. It will back out the garage ok, but as the noise slows to a stop-so does the car. Will not go forward or back. The OD light is not sending a code. The fluid is full and does not smell burnt. Does not leak, and recently added 1/2 quart. of Toyota Type 4 to top it off. I have noticed it seemed confused about a gear change 2-3 times in the recent past. Also, I had it sitting for 2 weeks while doing the brake pads (got busy with other things), and the battery had gone flat. After checking for codes, I tried an ECU reset, but it did not help. I saw where you could unplug the ECU on a Supra and test the box for manual gear change, but it appears on SC's the ECU is combined with the engine ecu-so no test driving. Do I need to short the diagnostic plug for the OD light to throw a code? I see some problems are due to bad grounding. Anyone see that cause this problem? What's the best way to trouble shoot this? Thanks, new here from Texas. Maybe time for a JDM or rebuilt with a shift kit and high performance torque converter?

I've found a 94 trannie but not sure of the month. I see where they changed in 2/94. Does anyone know what changed, and will it work on my 93? Where is the data plate on these cars?