CRuby

iTrader: (1)

I've been looking for a replacement ECU for my car: 92 SC400, 1UZ-FE, AT.
Finding some with slightly different part numbers & was wanting to know if they are compatible.
My ECU is pictured on bottom. Is the ECU pictured on top interchangable with mine? Note part numbers off by 1 digit.

Other: 89661-24240, 175000-4434, Big 31, 40P-40P-40P
Mine: 89661-24230, 175000-4424, Big 30, 40P-40P-40P
My car does not have Trac control, so possibly that is difference.

sc-driver

iTrader: (7)

what year is the other sc400?

CRuby

iTrader: (1)

Other is quoted to be from 92 SC400 also.

sc-driver

iTrader: (7)

you should be fine.

CRuby

iTrader: (1)

sc-driver, Are you speaking from experience on having done this before? I've been doing some checking on the p/n's & it seems like the "other" -24240, is for SC400's with Traction Control (T/C). My car doesn't have T/C, so I'm concerned that it may trip CEL when it looks for T/C signal & doesn't find it. I don't know that will happen, it's just I don't want to discover it after I brought the ECU. I just don't want to throw $$ down on a unit that may not be compatible. If you can give me more insight to why the swap'ss OK, I'd appreciate it.
I'm not suggesting you're wrong, it's just that I'm cautious. I've had someone tell me the ECU from a 92 LS400 is compatible too, however, my checking shows the pinouts are completely different. So without knowing you personally, it's hard to blindly trust.

Any other high-time CL members out there agree this swap is OK? I'm cautiously relying on your combined experience while the car sits, awaiting purchase of another ECU.

sc-driver

iTrader: (7)

Hmmm. If toyota was smart, the ecu's wouldn't be different for traction control.

I don't think I've heard of problems relating to traction control at all but double check with search.

But otherwise an ecu from 92-94 are interchangeable. I think 95 can be interchanged too. 96-97 are interchangeable. and 98-00 are interchangeable.

But I don't think the SC ecu is interchangeable with an LS ecu.

I've swapped out my 96 ecu with another 96 not even knowing whether it was traction controlled or not and I did not have problems.

Track5tar

iTrader: (2)

matches fine from experience...friend of mine had exact one. found his at local "U Wrench It" yard..

t2d2

iTrader: (8)

Bumping an old thread since I have the same question. My '94 SC400 (no TRAC) ECU is part #89661-24231. I just learned that I've got some pretty bad damage... Most of the info I've found says any '92-94 ECU with the right 40-40-40 pins will work, but nothing sounds very conclusive.

Has anyone successfully matched up identical (for all intents and purposes) part numbers?

ArkLaTexSC

Just get it repaired. Other ones will "work" but not perfectly unless all the variables (options, etc) are equal.

t2d2

iTrader: (8)

Sort of what I feared. Unfortunately, I don't think mine is repairable. Several of the pins between the wiring plugs and the circuit board are pretty badly corroded, and that would be quite time consuming to de-solder and re-solder all 120 of them to be able to remove the lower board and make repairs to the bad traces for the affected capacitor. I'm in the process of checking with a few repair services to see what they think, though.

Options are pretty limited for used ones with my part # (not a single one listed in the classifieds here, as far back as the search goes), so I may have to go with an eBay one and hope that it's in good shape other than maybe needing new capacitors.

ArkLaTexSC

Darryl will fix you up for sure.

t2d2

iTrader: (8)

Who's Darryl? Oh, probably Darryl Geller from one of the eBay listings?

ArkLaTexSC

Bingo. He's the man.

t2d2

iTrader: (8)

Here's what I've been able to piece together while awaiting responses about used ECUs and repair services:

#89661-24410 = From 01/1994 w/ Federal Emissions
#89661-24231 = Before 01/1994 w/ Federal Emissions
#89661-24240 = Before 01/1994 w/ California Emissions

"From 01/1994" equates to '94-95, but I'm not sure if that means it's OBDII. I'm guessing there's another one that came later in '94 which is strictly OBDII. My '94 was built in '93, making it easy to get confused on model years vs calendar years.

There's also a remanufactured unit available from A1 Cardone, part #72-10849 for the 24231, but they seem to be limited stock and double the cost of serviced units.

Oddly, I haven't found any ECU differences attributed to TRAC. Does that have its own computer, maybe?

KahnBB6

iTrader: (5)

t2d2,

Trac is a separate computer, yes. At least the SC300, SC400 and all MKIV Supras are set up that way. I assume GS/Aristos are as well.

As to whether or not any automatic ECUs from 300's or 400's are different depending on whether or not they are set up to talk to the Trac ECU I can't say but it shouldn't be the case. Your wiring harness will likely determine that. I cannot say if the two ECUs truly operate 100% independently from one another but it is very possible since disabling Trac does not affect normal engine operation (other than a dash light, perhaps).

Those part numbers should be easy to apply to your car by checking your vehicle's VIN code with Lexus or on an online Toyota parts EPC. Either will give you the build date of the car.

If you are unsure as to whether or not you have a California emissions or Federal SC400 you can try the VIN or just look under the hood and view the stickers underneath it (assuming your car has its original hood).

94-95 models or P/N's are still OBD1. OBD2 models are 1996-1997 for non VVT-i and 98-00 for VVT-i respectively. The distinction between pre-94 and post-94 may have something to do with pin count, pin arrangement, revised ECU programming for some reason, or another factor.