The transmission in a LS400 I'm working on is very rough when coming to a stop and will occasionally stall the engine, similar to stopping a standard without pushing in the clutch. It is rough about half of the time, and works fine half the time. I suspect the problem is with the TC lockup solenoid, but I'd like to confirm the best I can before buying the part and tearing into the transmission.

When I first started working on this car, the transmission was much worse, and would up shift erratically as well. I adjusted the the TPS and Throttle cable, and replaced the fluid with fresh Type IV. The transmission is now very smooth except when coming to a stop.

I also inspected the trunk wiring as has been suggested for many problems, but I didn't find any problems there.

Has anyone had a similar issue, and what did you do/have done to fix it?

Also, does anyone know the ECU pin for the TC lockup? I'd like to disable the lockup as further confirmation that the solenoid is the problem. I found a pinout for 90-92, but it appears 93-94 is different.

 

did you check all the pulleys along your belt? a few years ago one of the pulleys was bent (dont know how that happened) but it would stall as well. unfortunately, it was a big job to replace the pulley because of the location, took a few days

Im a newb though, so dont take my word unless anyone else backs that up