CelsiorN1

Hi everyone. I recently had the usual failing ecu issues of intermittent stumbling and stumbling after a hard run, unsteady idle and slowly dropping fuel economy. So I went to swap ECUs, but I may have triggered another problem unintentionally. It didnt start, just cranked. I figured okay this ECU isnt conpatible with my build date LS, so I swapped back my original ECU. It did the same 'crank no start' issue. I have looked for the past few hours all over the forum regarding the issue but no luck. Thought it triggered the immobilizer but no or else it wouldnt crank at all. Fuses seem fine but could double check them once more. I know its not the MAF cause Ive swapped it 3 times with other same part # MAFs. Its definitely something electrical but cant quite put my finger on it.

My Lexus is a '96 LS400 US SPEC and I may have used the wrong ECU. My original ECU is part# 89661-50303. The ECU I swapped in was 89661-50341. Mind you, theres too many ECU combos for me to remember all ofem and their differences haha. Any help would be appreciated guys, thanks!

RA40

iTrader: (6)

Yamae's ECU list is here:
https://www.clublexus.com/forums/ls-...ica-yamae.html

The later variants of the 97 had the ignition immobilizer coding. Not sure if the pin out would be the same even if they plug in. Yamae may know if that ECU may have had effect on something downstream. Can check fuses. Other than that, IDK.

Yamae

You used a wrong ECU. As RA40 has pointed out, an ECU 89661-50341 has an interface with the immobilizing function circuit and those two are not fully compatible. When the code is not matched, the ignition system is disabled. Without analysing your car myself, I can't tell what is causing your current problem. What I can suggest you at this point is to read the error code first using a good scanner. I don't think an ECU 89661-50341 damages sensors and other lines connected to output pins, but the charged +B or a static discharge might damage your car. If you can't read it, try using another good ECU.

CelsiorN1

It didnt give me an error code but I will try another ecu since I need to get a replacement anyways. So far, everything works except the ignition like you mentioned so its a matter of finding how to get it to get out of shutting off the ignition system. I had put back my prior ecu that was still fuctioning well enough so I figured it may have been that, but it still refused to fire up.

CelsiorN1

97celsior702

I have a 1997 celsior and started experiencing what I believe is ecu problems so I ordered an ecu repair kit and a spare Ecu to make sure I wasn’t stuck with a car I couldn’t move. When I installed the spare Ecu, which shares all of the same part numbers the car cranks and doesn’t start. I believe it has something to do with the immobilizer. If someone has a solution or may know what my problem is I’d love the help. Holding off on the Ecu repair till I can get the spare one to work. If that dude yamie is still alive I think he would have the solution to my problem.

400fanboy

When was your 97 built? I think the very beginning of the production run did not have an immobilizer, but I'm not sure when that switched over. Nor do I remember how Celsiors differ. But to me - it sounds like an immobilizer. It kills the EFI - crank but won't fire.

You cannot replace just the ECU. Adding one from a different car may not work as these units are coded from Toyota with specific programming and with a specific key. You'll need the master key and matching ECU along with the wiring harness, amplifier and who knows what else. I believe it may be possible to reprogram new keys - but this is a hazy area. There are no good or easy solutions here. If you want to DIY bypass it yourself... good luck

https://www.clublexus.com/forums/es-...apped-ecu.html

https://www.clublexus.com/forums/ls-...-solution.html

I suggest you try and get your original ECU working and return the spare, if you can.

97 is the worst of the worst for these cars. It had the immobilizer lock - while also being the most vulnerable to the capacitor failures. 98+ the cap failures are far less common, though I believe also inevitable.

Yamae

In case of a 97 Celsior, you need to start to specify the manufacturing date decoding from the car ID number. Depending on the date, your action would be changed. a 97 Celsior is not the same with a 97 LS400, you need to know first. http://oliac.com/autos/index.php