eicca

Here's what I would do: Buy an ECU with a master key from eBay or something. Install it. Use the key blade you have right now to turn the ignition ON while holding the key that came with the ECU up to the ignition cylinder. (If possible, transplant that transponder into the key that doesn't have one). This will turn the system on and the transponder will allow the car to get into programming mode. Once it's in programming mode, stick in the new key that you want to be the car's new master and program it into the ECU.

crossface

So it's not possible to order just the key with an immobilizer chip installed & switch out the key blade so it'll allow itself to enter programming mode? There's a seller on eBay that says if you send the key code to your car that he can cut the key specifically to your ignition & it appears to have the remote head on the key. Would that not be able to be programmed? Or am I completely missing something here. Or even worse, is there just no way about getting around to having to replace the ECU? If that's the case, there's also another seller that's selling an ECU & a key, but my question is, how would that key be able to properly fit my ignition? I do appreciate all this input. Believe it or not, it is helping me to make the correct decision about this whole fiasco.

eicca

The ECU currently in the car is programmed with a certain transponder. That certain transponder is supposed to be on the key blade you have, but it's missing. Without that exact transponder, your current ECU will not enter programming mode or start the engine. You HAVE to get a new ECU.

Like I mentioned, what you can do is get a new ECU from eBay or from someone here selling one, as long as it comes with a master key. That's critical. Swap in the new ECU.

After you install the new ECU, tape the key it came with right next to the ignition cylinder, and then use the key blade to turn it to ON. The new ECU should read its transponder and you can then put it into programming mode. The ECU couldn't care less what the physical key cut looks like, it's only looking for the signal from the transponder switch.

Once you've gotten into programming mode, you can program in your new key of choice, because the key the ECU came with is guaranteed not to be cut for your locks and ignition.

If you get lucky, you may be able to swap the transponder out of the key that comes with the new ECU into the key blade you already have. That would be a plug n go solution.

crossface

So another words, after placing the old key into the ignition & all goes well as far as programming, the different key that's being sent to me isn't going to cause any issues as far as the cut of the new key is concerned? I just thought that the cut of the new key would have to match with the tumblers or whatever the technical jargon one would use to be able to properly fit the ignition cylinder. That's where I thought that the key blade cut would matter. Huh. Who knew? Well obviously you do, & that's why I TRULY appreciate you bearing in mind patience with me. I'm not above purchasing the new ECU on eBay, I just want to make sure that I'll be able to at least start the car. We are talking about a $220 purchase! As I stated before, thank you so much for being patient with me & walking me through this whole thing. And I do apologize before hand, as I'm certain I will probably have more questions.

eicca

I think there's a small disconnect in understanding going on. I'm not sure if I'm missing your explanation, or if I'm being confusing. Hang in there, we'll solve this.

Let me start from square 1 and see if that helps.

To start your car, you need A) the physical cut of the key, where the grooves in the key will allow the locks/ignition to turn, and B) a transponder chip that will tell the ECU to activate.

You currently have A. You are missing B.

A new ECU from eBay should come with a master key. This key will have C) a physical cut that does not match your locks or ignition, but it does have D) a transponder that the ECU accepts.

When you swap this new eBay ECU into your car, your existing key A will still turn the ignition, but the ECU will be looking for transponder D and so it won't activate.

Transponder D is tied to the ECU, and key cut A is tied to the car. So you've got two halves that have to be combined to start the car or get into programming mode.

With me so far?

crossface

Yes. I definitely understand what you are saying. By the way, just got a response from the seller of the ECU unit on eBay. The response was that "the key that is being sent with the unit is only used for programming the key that I already have to make it operational with the ECU that is being sold." So I'm just wondering, is this gonna work? I can send you the link to the unit for you to look at for yourself to let me know whether or not I'm still up a creek without a paddle. Entirely up to you. I feel as though I've consumed enough of your time without you having to scroll about on eBay to see whether or not this is possible. As I stated before, I TRULY appreciate your patience on helping me out with this whole situation. It's a rare trait for people to take time out to want to help other people out. By the way, sorry if I double posted this, I went back & checked the status & it didn't post the first time. Just let me know about sending you the link. I truly do appreciate it.

eicca

Yeah, send me a link.

Regardless, buying a new ECU with a key has to happen to resolve this situation, so find one that you're comfortable forking out dough for.

crossface

Alright. Here's the link.
http://m.ebay.com/itm/Lexus-Gs400-1999-Ecu-With-Key-/322452663909?nav=WATCHING_ACTIVE

crossface

I've also considered going this route as well, which seems to me to be the sure fire bet, with the exception of removing the locking cylinder, but at this point, I have no problem doing.

http://m.ebay.com/itm/Lexus-engine-ECU-ECM-reflash-Lost-key-replacement-service-Programming-keys-/182252713160?fits=Year%3A1999%7CMake%3ALexus%7CModel%3AGS400&hash=item2a6f1bb4c8%3Am%3Amrqx-rVwC7edXT6RIXYWS0w&_trkparms=pageci%253A45970ed1-0b0c-11e7-8516-74dbd1800da9%257Cparentrq%253Adc37595415a0a357b5152e7ffffbd89f%257Ciid%253A1

eicca

Just buying an ECU with a master key would be easiest. That ebay link looks like it should work. Yours is a 1999, right?

crossface

That is correct. It is indeed a '99. So by all accounts, everything you read, choice A, the ECU & key for sale is the easiest way to go. When I purchase this I should be able to do everything you said about programming the key, etc.? Alright. Well, it sounds like that needs to be the route I go. That's kind of what I was thinking all along. I'm not really to keen on the idea of disassembling the door to remove the locking mechanism. Knowing my luck I'd screw up the actuator motor or break the glass or something extremely dumb. I just know me & my luck so far with this car. I really appreciate you taking the time to examine both links & seeing which would be the best direction to take. I just hope the whole "taping the new key to the steering column & using the key blade to program" thing works. If not, well, I don't know what I'll do.

eicca

Yeah, don't bother monkeying with the locks. Just get a new ECU and key. Your problem can be solved.

TW99GS300

How handy are you with a computer and soldering iron?

crossface

Unfortunately, not very good. But that's alright. I've decided to take a break from trying to immediately trying to figure this out. I've had a few financial snags that have outweighed purchasing the car right away, plus I figure it'll give the seller time to try & locate the missing key. Like I stated before, he & I have a pretty solid relationship having worked for him for several years, & I'm CERTAIN the car isn't going anywhere. Not to mention that in the midst of this fiasco with the key, it seems as though the title for the car has been misplaced as well. So with that being said, he had to send off for a new title. So really at this point, I'm in no rush.

crossface

So, update time. The seller found the key! When I received the key, I found there to be absolutely nothing wrong with it. The shell casing was cracked & glued together. The key blade was loose & the battery was dead. Replaced the battery, tightened the screw slightly, & electrical taped the cracked shell casing as a temporary fix. Plan on ordering a new shell casing & transplanting the transponder soon. Very happy. I'd like to give props to everyone who advised me on this post. This site is awesome, and all the members are equally as awesome. Bet for sure that I'll be referring back here for whatever issues I may encounter. Special thanks to Eicca. Your time & patience were invaluable to me.