I'm having a tough time making sense of the instructions for programming the '98-00 key and/or remote.

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Summary of what we've determined:

The remote key's transponder chip is part of the remote module, not part of the key blade. I received my Eternity Key (thanks Blkexcoupe for the recommendation, it does indeed feel much more stout than the regular 3-button shells) and confirmed that no programming is necessary. Just swap the remote over and the immobilizer recognizes the new key.

The limit of 4 "keys" is a safety feature since there's a fair bit of overlap across remote codes. (It's actually 4 slots in the wireless computer. Whether or not the immobilizer also limits the number of transponder chips is uncertain.) Fewer key storage slots means fewer chances of someone else's remote working on yours. Following the steps in link #1 programs the wireless computer to accept remote lock/unlock signals. It isn't actually adding keys to the immobilizer, despite what is implied by the instructions.

The steps in links #1&2 (below this summary section) do work for our cars, although I had the best luck (after several tries) with a combination of the two sets of instructions:

1) No key in ignition, driver door open, passenger door closed and locked.
2) Insert key in ignition and remove.
3) Lock & unlock the door (at the handle, not the power switch) 5x.
4) Close and open driver door.
5) Lock & unlock the door (at handle) 5x.
6) Insert key, LOCK -> ON -> LOCK. Door should lock/unlock itself once.
7) Press Lock/Unlock buttons on new remote simultaneously for ~3 seconds. Release both buttons. Press Lock button briefly.

Step 7 is the part I had to experiment with. Pressing the two buttons briefly like in link #1 didn't trigger the learning mode, nor did pressing the Unlock button after holding both down for 3 seconds like in link #2.

I tested the above with the existing remote removed from the key, as I wanted to confirm that the remote/chip is not necessary in order to enter wireless programming mode. All that's needed is a Master key. The "Adding a Key" factory instructions pertain to using the buttons on the new remote, not the old one.

I struck out on programming the new remote's transponder chip into the immobilizer, following the Program E instructions for common '98-00 remotes. However, this page has a slight variation of the "pedal dance" that proved successful:

http://www.lexusownersclub.co.uk/for...rting-the-car/

1) Press the accelerator and brakes pedals simultaneously ONCE, then release.
2) Insert your Master Key into the ignition, and turn ON.
3) Press and release the accelerator FIVE times (within 15 seconds)
4) Press and release the brake pedal SIX times (within 20 seconds)
5) Remove the Master key
6) Insert the new key into the ignition, and turn ON (within 10 seconds)
7) Press and release the accelerator ONCE (within 10 seconds)
8) WAIT 80 seconds (or so), the security light should go OFF.
9) Remove new key, press and release brake ONCE. - Done.

The key (no pun intended) difference between the two sets of instructions is whether or not to turn the key once inserted.

Programming of the transponder chip for a non-remote key hasn't been tested, but I assume it would work just the same as above.

Post #14 here shows the immobilizer chip, which looks like it could probably be swapped between remote fobs.

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The original post follows...

First of all, there are numerous slight variations of the instructions out there, such as:

1) https://www.clublexus.com/forums/ls-...ml#post6103432 - remote programming, factory instructions
2) https://www.clublexus.com/forums/ls-...-99-ls400.html - remote programming, slight variation
3) http://www.automotiveforums.com/t657...xus_ls400.html

Following the factory instructions in the PDF linked in #1 leads me to the first area of confusion. Namely, how do you differentiate between programming the key's transponder chip and the remote? The instructions only refer to registering the key code, but you use the remote to do so. Does that mean both are being registered in conjunction? That wouldn't entirely make sense either, though, because don't you have to be using a previously registered Master key to even enter programming? (Maybe I'm confused on that point, too.) In which case, it's the registered Master and unregistered remote being used in the outlined steps, so only the remote would be getting registered.

The instructions in #2 didn't work for me exactly as specified, but substituting the power lock switch for the inner handle lock button got the desired confirmation result, but it was the same 2x unlock/lock cycle as #1, meaning unsuccessful registration. #2's instructions are specifically for programming the remote, and they're essentially the same as #1's.

Also, I did the Confirmation Mode test in #1 and only 3 of the 4 slots are registered (I only have 2 of the keys; one Master + Valet), so that's not blocking adding a new one. There's also uncertainty from the earlier Build Thread conversation as to whether adding a 5th bumps the oldest off or requires starting from scratch.

One possibility is that both the remote and the key are registered simultaneously, meaning you don't use a previously registered Master to enter programming mode, and that it's blocking me from doing so because I'm trying to use a registered Master which it sees already in one of the 4 slots. I could see it disallowing having the same key in there twice.

There's also this: showing which '98-00 models share the same remote. Fittingly, its Program E instructions are completely different from the others! Would that process be used for registering a non-remote key, perhaps?

Hopefully, we can outline a clear set of steps that we know works for the SC, and have it documented for others down the road.

p.s. My reason for asking this now, rather than when I have a new key cut once receiving the title in my name, is I came across an ES300 remote today and wanted to see if I could get it programmed in as a backup. As such, I'm doing so with the registered SC Master and unregistered ES remote. It's further complicated by the ES' Lock button not lighting up the LED reliably (it had a dead battery, so I didn't realize it right away), making simultaneous pushing of both buttons difficult.

 

That link in post 1 is 100% wireless lock system. When you are doing the lock unlock routine, the wireless door lock ecu is pretty much waiting for a signal from the new remote, or key (with built in remote). When you get to the section where it tells you to hit whatever button on your remote, that's when it picks up that key (with built in remote).

One thing to note. Your key has an fcc ID stamped on the back of it. Your wireless door lock ecu also had an fcc ID label on it. If they don't match, the remotes typically won't work. Your owners manual will actually have the fcc ID listed in it as well for your car so if you ever need to replace the key (with built in remote), you can get one outside of lexus. An ES remote may or may not work for you. It all depends on the fcc ID of the wireless ecu for the es.

I can't stand the remote in the key, so I swapped my wireless ecu to one from a 96 and bought the appropriate remote off eBay and programmed it with the external remote

 

Really? :/ I thought the Max 4 registered keys aspect is the ECU/immobilizer, not a wireless lock thing, since the non-remote keys count toward that? At the very least, the wireless lock system has to communicate with the ECU for Confirmation Mode (2nd page of the PDF) at some point...

Are you saying it has to be a key being recorded in that last step, and optionally corresponding remote? As in, what I was trying to do with registering just a remote won't work because there wasn't an unregistered key to go along with it?

It's the same FCC ID # on both. I hadn't thought to check that before, but I'm not surprised given that the last link in the first post goes to a PDF saying they're the same unit.

​What about it didn't you like? I didn't realize you could run an earlier wireless lock system. How did you then program the remote? Did you use the factory lock/unlock steps or something specific to the replacement remote?

 

Partially correct. It communicates with the wireless door lock ecu. The wireless system and immobilizer are 2 completely separate systems. The 4 keys thing is just security. It maxes out at 4 so every Tom **** and harry doesn't have the ability to unlock your car. I have actually hit the unlock button on my celica remote and it unlocked my car, and a car 3 spaces over. It's really kind of a basic security feature.

You can take the screw out of your key and split the cover, then take the remote circuit board physically out of the key and it would still operate your locks. Just so happens your key and remote are housed in the same unit. The pdf file is solely for programming the wireless door locks. Nothing more, nothing less. The 98+ keys have 2 distinct parts, the blade/rfid portion for the immobilizer, and the wireless remote circuitry.

In thoery, you could swap any wireless lock system in as long as it was compatible with your lock actuators. I suspect most lexus actuators are the same type. In my case, the 92-95 has the single button on the side of the key. Not very full featured. I also don't like the thought of the blade breaking off of the key itself. I opted for the 96-97 setup which uses a pretty standard toyota 4 button remote. I had an old 96 wireless ecu and aside from having to re-pin a wire in the pigtail, it was plug and play. I still have to run the wire for the trunk pop but that's easy. I used programming instructions applicable for a 96 sc4 (what the wireless ecu came from). I bought a couple of used remotes off eBay that matched the fcc ID

 

Okay, I'm starting to catch on now. So, the Max=4 piece is purely the wireless lock system, not a limit within the ECU/immobilizer. In which case, the factory instructions are misleading when they say "Adding a Key," as it's really just adding a remote.

However, that leaves me confused as to how/where/when the transponder chip in the key gets programmed for the immobilizer. That must be a completely different step I haven't come across yet.

I didn't realize the wireless codes are so limited as to be frequently duplicated. Classic Toyota move, with interchangeable keys. That makes Prohibition Mode, or just removing the wireless lock ecu, somewhat appealing.

I'm guessing that the importance of the Master key in programming the wireless lock system is the part where you insert it in the ignition (LOCK-ON-LOCK), which probably tells the immobilizer the chip is okay, which then activates the wireless ecu for learning?

Yeah, that's what I was hoping to accomplish with the ES300 remote, since its key was broken off and of no use to me, anyway. I'm guessing I just need to get around the problem of the buttons not functioning reliably on it.

 

You are correct. While I'm sure the immobilizer has a limit as well, it's separate from the wireless.

It is. As far as I know, unless you zero out the eeprom for the immobilizer, adding keys is a dealer only (and maybe some locksmiths) service. This would be one of the reasons why there is no programming routine in the TSM. They don't want just anyone being able to program the immobilizer.

90s technology at its finest.

The significance of having a master key for programming in your situation is the fact that valet keys don't have remotes built in. That's why you have to have a master.

In wold take it apart and clean it up if you haven't already.

 

Actually, I have to correct myself. I did run across something that might be for that: the rather confusing "key transponder application guide" pdf. The title should have been a hint... My memory was jogged by these two threads:

http://www.lexusownersclub.co.uk/for...nt-lockunlock/
http://www.justanswer.com/lexus/3li1...g-battery.html

Neither is for our car, but they both reference that general approach and the second one actually differentiates between remote and key programming.

Right. I just meant that the Master is likely initiating the process with the wireless ecu, telling it it's okay to enter programming mode.

That's the first thing I tried, but other than removing the battery cover, there isn't access to the buttons and contacts. Maybe there's some way to pry the two halves apart with the battery cover unscrewed? I suppose there's no harm in trying, since it's either dead or dead.

Edit: Yeah, it can be opened up with some careful separation of the black layers sandwiching the clear layer. Cleaning everything didn't make the button work any more consistently, though, so it's probably bad circuitry and only useful for spare parts (casing, buttons, screws, battery cover). Oh well. At least I know now that there's no significance to the remote for programming new keys, like I initially though, so no pressing need to have a spare.

 

The RFID portion for the immobilizer is part of the wireless remote circuitry. I've snapped a few keys and had a new key shell cut without programming. I just swapped the little 3 button transponder into my new shell and the car starts up fine. If I try starting the car without the transponder being present then the car won't start.

 

Hmm I stand corrected on that then.

 

Argh, just when I thought I was "getting it." So, the LOCK-UNLOCK procedure sets the remote's code into the wireless ECU, and the brake pedal procedure sets the remote's transponder chip code into the immobilizer? Or is the transponder chip writable and it receives a code from the immobilizer? Not that it matters, just trying to sort all this out.

Is the transponder chip a proximity thing or a sensor directly within the ignition? Did you try it with a programmed remote in the car but not on the newly cut key? I suppose I could test that out myself, since I currently have the remote removed from the Master key. If work wasn't kicking my butt today, I'd be out playing with the car right now.

 

I'm not sure. I've never looked into it before. I just know the basics based off what the lock smith explained to me when they ran into issues with my car.

The transponder has to be attached to the key. I had the broken key, the transponder, and my good key in the car. I tried starting the car with the broken key, and it didn't work. I also tried starting the car with the broken key and the transponder right next to the ignition, and it still wouldn't work. When I used my good key it finally started up.

 

That's puzzling. There's only plastic and air between the key blade and the remote unit, so I can't imagine there's anything making contact between the two as far as completing a circuit. Unless the range of the ignition's sensor is limited to the length of the key handle, it seems like having the remote/transponder in your hand would have to be the same as it being part of the key. But...I went out and gave it a try, and you're right. Even with the remote right next to the key, the car cranks but won't start. Maybe it has a 1", direct line of sight limitation to the range, so even being off to the side doesn't work?

 

I confirmed that the transponder chip is part of the remote. I've updated the first post with a summary of what we've arrived at, and will continue to do so as new information comes along, since this is sure to be an area of confusion for many people.

 

In case you are all wondering the immobilizer chip is the little black piece that is found on the corner of all 3 button Lexus remotes. It's not connected to the circuitry or powered by the battery at all which is why it can be programmed and still function when the remote battery is dead or missing. Here is the picture of the chip on my 1998 SC300 remote.

 

^ Excellent addition, thanks.