Hi guys i hope you doing alright, I just bought my first lexus, its a 98 model non runner The car has been sitting from 2018 and its not starting(it cranks). Ive been all over this place before i write this and still got questions. The fuel pump wasnt starting on ignition so Efi wasnt working and i changed it, pulled out the pump and test it on the bench - it worked, changed the open circuit and fuelpump relay as well, pump still wasnt working so i connect with cable + from the OC relay and + from FP relay(when i just connect + and + from OC relay something happens and another relay getting on and off all the time) and now pump is working fine. The car however still doesnt start. I took the ecu out, opened it up and looks fine, yet i went to repair shop and ask them to inspect the capacitors and they told me they are fine. Now im wondering if the immobilizer is playing as the security lamp never stops blinking (not sure how it should be) and i only got a spare key(no fob or buttons) for the car as previous owner lost the master key. Also can you guys tell me where should i look further as im getting lost, can the ecu still be bad if all the capacitors are working fine? Sorry for the long post and thanks.

The red immobilizer indicator should stop blinking when a matched key is inserted. Continuous blinking simply means that the code is unmatched or the code is not properly recognized by the ECU.

Thanks a lot! I will now find a second hand key with fob and program it to the car and see what happens.

You need a master key to program any additional keys.

I would think the dealership would be able to program a master based on VIN. At least I hope they would.

Hi, from what i read, a master key ia concidered any key that has the transponder chip in it. Am i wrong?

Correct but it seems that the ECU is not recognizing your key and will not start the car. I don't know if this is in fact what's happening so giving it a try can't hurt.

Yeah, i believe thats whats happening as i dont have a master key now. I found one from the scrap yard for 40 quit then i will gwt an empty housing and blank key, will cut it and transfer the chip then program it and hopefully it will all work well 🎉👌🏻

Can you unlock the door or pop the trunk with your present key?

Communicated with an ECU programmer
on LS430 ClubLexus Forums.

The LS430 ECU is more amenable to performance reprogrmming, but not so for the LS400 ECU, EXCEPT that he can disable the immobilizer security function...where you do not have the original key...

Yes i can but there is no transponder in my present key.
Hi, so are you saying that i cannot reprogram another master key to the ecu and start the car?

Not saying what you can or cannot do...but am presenting an option if nothing else works.

A quick call to dealer parts department will more fully advise you of available options.

Make sure you talk to someone who is not a newbie

Hello guys, thanks for the help. I finally got a used key chip and new key cut for my car. I used the steps to program it and it worked for the keyfob lock/unlock function but it does not work for the immobilizer. All sorts of immobilizer programming im finding are with original master key which i dont have so if anyone know a way will be nice otherwise, i will try to find and locksmith and see what he can do . Thanks again!

A master key is identified within the ECU's immobilizer programming. None of the keys you have seem to be flashed to the ECU, so none are master keys that you can use to Add keys to the system. You will need to remove you ECU and have it reflashed for your keys. The ecu immobilizer and keyless entry are 2 different signals. Check out https://www.ezcarkeys.com/Lexus-Lost...ce-LexusLK.htm I used them to have keys made for my 1997 LS400, very similar process as both have an immobilizer. They were literally the only people out of MANY, including my Lexus dealership, that knew how to get my 97' back on the road with no keys. Good luck!