xspsi6

iTrader: (31)

I took these seats from a 00 for my 97 now the memory function does not work on the rear bottom cushin up down function is inop and they for sure worked before I did the swap.

does anyone know anything about this?

Ali SC3

iTrader: (10)

if any of the functions are not working on the seat and it was in the memory to move the seat that way, the memory will stop working till you unplug and plug it back in. reprogram the memory without using the function that doesn't work. have to remove the plastic cover on the door and unplug the memory unit and plug it back in, well at least that worked for me when my lower cushion stopped going up and down also. it might just be broken on the new seat.

xspsi6

iTrader: (31)

Ok so would just disconnecting the battery work? The seats came from a cherry 69k mile sc300 and i know for a fact every function worked before i pulled them so it happened between the transferring of the seats also the memory still works for the mirrors and steering column.

t2d2

iTrader: (8)

Did you double check that the wiring harnesses have all the same wires? I would assume all years' seats are interchangeable, but maybe not, being the last year.

xspsi6

iTrader: (31)

Not yet but as ali sc3 said i unplugged the buttons from the door and now the memory function wirks just not the lower cushin rear adjustment feature.

Ali SC3

iTrader: (10)

Yeah not sure why it would fail but I know that is what causes the memory to freeze. from what I remember unplugging the battery didn't work, I had to pull the the connector and plug it back in, but maybe I didn't wait long enough can't say for sure but the unplug replug should always work.

xspsi6

iTrader: (31)

Good to know!

horent135

iTrader: (10)

Maybe the chairs you got are bad from the beginning? I got my seats from 00 and put in my 98, everything works perfect from the first plug

mfg_guy

If your 97 has a manual transmission, you need to swap the seat ECU's on the underside of each driver's seat. Manual transmission seat ECU''s are different from automatic seat ECU's.

t2d2

iTrader: (8)

Really? Why would that be?

mfg_guy

I can't recall right now, I will have to look it up. But I had the same problem when I swapped my 98 seats for 97 seats that were from a manual car. The ECU's have different part numbers. If you check the p/n on the two seats you will notice they are different.

t2d2

iTrader: (8)

If the seat ECU is different, then wouldn't the harness to the seat be different, too? That or the seats themselves would have to be different to account for different ECUs with common main harness connections. Unless there's another possibility I'm overlooking...

gerrb

iTrader: (34)

The SC having a manual or auto transmission has nothing to do with the Driver and Passenger Seats ECUs or wiring .

In fact , I just finished inspecting the wiring diagrams for those Seat ECUs from 1992 up to 2000 ... they are all the same for SC300 / SC400 either with auto or manual transmissions except for the 1992-1994 passenger seats having less controls . I have personally confirmed this in the past on my cars since I have moved seats around from my 1992s to 95 to 97 and vice versa.

here is the wiring diagrams for those seats and their ECUs... which is basically same from 1992 - 2000 cars . I can post every seat wiring diagram of every year of SC here but are basically the same with this.

mfg_guy

Well I could be wrong about the manual part because I swapped my 98 unheated seats for 97 heated seats, and the 97 seats were from a manual. I'm not sure if it would have made a difference if the 97 seats had been from an automatic. But, I can say definitively that the seat ECU's were different part numbers and they were plug compatible. It was the different part numbers that clued me into why I was having problems. At the time, I had two 98's (300 & 400), one heated and one not, both had the same ECU p/n, and the 97 manual, which had heaters and a different p/n. I can also say that the diagram in the previous post does not match the diagram in the 98 SC Electrical Wiring Diagram manual. I haven't checked every item in my manual, but there is a connection from the A/T park-neutral position switch to the driver's side seat ECU ( connector/pin A15). I don't see that connection on the posted diagram. I would post the diagram from my manual, but it is 4 pages (pg. 208-211) and I couldn't get the photos to upload. Not trying to be difficult but would like to see the OP get the problem resolved. I would look as both cars are still available to me, but as I recall I would need to remove the seats to read the p/n on the ECU's.

gerrb

iTrader: (34)

No worries ... I don't see you being difficult at all. We are all trying to learn and help each other that is why we are on this forum. If I am wrong , I myself would say "I am wrong, my bad " just like you did on your first sentence on your previous post which is a very good attitude coming into a forum. Only d?ckheads do not know how to admit being wrong.

I would suggest you scan or take a picture of those 4 pages from your 98 SC Electrical Wiring Diagram manual and post them here so we can check them out and can compare them from the info coming from the Toyota Website and all learn.

Here are the pertinent pages from the 1998 Lexus SC300 / SC400 Wiring Diagrams coming from the TIS Toyota / Lexus Technical Information System which belongs to Toyota. It's their OFFICIAL Technical Info System. On that site you will find whatever info you want to know about any Toyota / Scion / Lexus car for whatever model and year from 1990 ... basically anything from descriptions , technical info, wiring diagrams, diagnostics and solutions to problems and others.

Webiste Link :

https://techinfo.toyota.com/techInfo...oyota.com%252F

Here is the particular page for the Driver and Passenger Seat ECUs of a 1998 Lexus SC300 / SC400.





If you trace most of the wiring from the Driver Seat ECU as shown above , they go to the power tilt / telescopic ECU and battery voltage supply as shown on the next picture .





The only pin I see from the Driver Seat ECU that goes to the Engine ECU which houses the transmission controls is on orange outline below




That wire that I outlined goes to the STP light switch and the STP Pin of the Engine ECU as shown here




Here is where it goes to the Engine ECU ... which is the STP Pin as show here




And that STP Pin has nothing to do with the operation of the Seat ECUs . It is common for cars with either Manual or Auto Transmissions. It provides an INPUT data to the Engine ECU and not vice versa.

Here is what that STP Pin is for :

Pin 4 - STP , Stop Light Switch , Input , This pin is used to detect when the brake pedal is depressed. Used to disable the automatic transmission lock up torque converter and exit deceleration fuel cut mode etc. This pin is connected to battery voltage when brake pedal is depressed, the ECU pin is open circuit when the brake pedal is not depressed.


My personal observations so far :

a) Manual Transmissions SCs were manufactured only up to 1997 . So if one is able to use seats from 1998-2000 which all have auto transmissions, that clearly says .. Engine ECUs that houses the transmission controls has nothing to do with Seat ECUs

b) I have a 1997 SC with manual transmission . I have moved around the seats from a 1992 , 1994, 1995 with auto transmissions to that 1997 SC and all worked . The 1992-1994 though have fewer controls compared to the 95-2000.

c) As per my experience , Toyota Part numbers may differ in different years .. but that doesn't necessarily mean they differ in construction or materials or functionality. A good example will be to compare the components of a 2jzgte Non VVTI ( 1993-1997) and 2jzgte VVTi (1998-2002) engines. Some of their internal part numbers on their catalogs are totally different but are exactly the same parts meaning there is no difference except the part number.

d) The differences I see on the wiring diagrams are only on the Passenger Seat of 1992-1994. They have less switches and motors . Though the Passenger seat ECU still looks the same based on its ECU pinning. The 92-94 only have slide and recline controls based on the diagrams on that site. The 1995-2000 has slide, recline , front vertical, rear vertical and lumbar support . But Driver side ECUs and controls are same. If I miss something , I stand to be corrected. But so far , on account of my investigations , if the OP has a 1997 car , he can move any 1998-2000 SC300 / SC400 seat and all functionalities should work. And for easy comparison below I posted the seats wiring diagrams from a 1997 SC and 1998 SC which led me to conclude they are the same....

1997 SC Seats wiring diagram


1998 SC Seats wiring diagram







For the sake of learning , I would strongly suggest take a picture of those 4 pages you are referring so we can compare them with the info from the Toyota / Lexus website so we can all learn .


Also here is the wiring diagram for the same year model 1998 that has heated seats. The heater components has their own switch on that transmission shifter cover. I don't see any connections to the seat ECUs .