last night i threw a used 160k mile 01 lexus gs 300 trans into my 04 gs300 as the old one had a solenoid out and the front pump seal finally blew. (257k miles) after swapping trans, making sure tq converter was set and torqued, all sensors were cleaned and connected, trans lines were connected, shift linkage was connected, and the rest of the drivetrain was all bolted up i filled the fluid up, let the car warm up and boom when i put it into gear absolutely nothing. revs as if its in neutral or park. no idle up or down when put in gear. i can hear and feel the trans go into the gears. manual mode doesnt do anything and on dash it goes into the correct gears. im lost with this right now and any advice would be super helpful. right now im gonna swap the 4 outside sensors from my old trans onto my “new” one and see what happens. could it be tcm not reading the new trans because its 01 not a 04? keep noted the old trans wouldnt engage into 4th 5th, neutral, or reverse, and was throwing code p0756 and code p2757

 

I don’t think they are the same transmission? I know in ‘01 they came with the 5speed A650E and by ‘04 they had upgraded to the 6speed A760E or something? Did your car come with a 5 speed or 6speed? I am not certain of the trans designations but I doubt your ECU can control the older 5speed? Did the wiring plug in the same? You would have to get an older ECU and modify to work with your engine probably more work than to just find a newer trans and swap em again? They usually last a long time, so there seem to plenty of used ones around for low prices? Where u located?

 

01’ A650E and 04’ A650E are the same mechanically.
However, even though the connectors and plugs ft were you able to verify correct wiring? There are subtile changes in wiring throughout the 2nd Gen life span. I have an 01 wiring schematic and as an example the wiring does vary from GS400 to GS300 in the same book.
verify the pins are in the correct place. I would start there.