Hey guys new to being a Lexus owner, I recently purchased a 97 ls400 with a bad transmission. I was wondering if anyone has done the 98-00 5 speed automatic swap in these cars? And if so was it a simple swap of just the shifter, computer and trans, or if it's a lot more involved.

 

Sounds like a great project...

Why not acquire a 1998+ ?

 

As far as I know, the ECU's in LS400's control the engine and the transmission. So to do that kind of swap you will need the ECU from the newer car, and pretty much all the wiring harness from it, as well as all the engine sensors, and since the newer engine also has VVT or what ever you wish to call it, you would then need the newer engine to go with the transmission, unless you have a program that will disable that function in the ecu, and along with all that you very likely will need the instrument cluster and any other black box that communicates with the rest of the CAN system in the newer car.
All this means pretty much gutting out the interior of the car and removing the dash etc. to access all the boxes and do the wiring etc.
Your other options are, using some after market transmission controller, and maybe even the engine would need one too, but then you loose a lot of other functionality from other things like trac if you have that and then of course you would have to figure out how to work the Air conditioning and stuff like that.
Maybe others have done it and have a trick to do it all ? I don't know.
The best option is to just buy the newer car that has what you want, and save a years down time to do the conversion and all the work and headaches that go with it.

 

Ouch haha yea I might just stick with the 4 speed then I appreciate the info!

 

TL;DR- Won't work because your '97 ECU won't work with the later trans. Way beyond a bolt-on swap.

 

The mechanical part is mostly simple. You'll need to do some wiring work - and the UCF21s were the first model with VSC/VVT-i and some multiplexing, Toyota didn't really use CAN until the early 2000s. That's the hard and painful part. I'd find a 1998-2000 car in good shape.

 

I agree w/ PureDrifter and dicer ... I've owned a 1996 LS400 and a still own a 1998 LS400 so I've had some experience with both. The 95-97 models have a "A340E" transmission and I believe it is a 4 speed. The 98-00 models have a "A650E" transmission and is 5 speed. I do not believe these transmissions are compatible and won't bolt up to each other either. You would basically need to do a complete engine swap and then some. It would be a bit of a headache rather than just getting the "A340E" trans that belongs with the car.