jeyzeus809

So I bought a pretty mint 1997 LS400 not too long ago. It's the best car I've ever owned, I love it. Anyway, I needed another key for it since I only had one master key. I felt like there was a lot of contradictory information on the web posted throughout the years on the process and which key to get out there so I just wanted to make a new post on the topic and clear it up for anyone searching. If you only have one master key for your 1997 LS400, I highly recommend getting replacements made ASAP. Apparently if you lose the only master key you have, it's a pain to get a new key.

A couple of things I've found out.

- The 1997 LS400 has a different method of pairing a new key to the car than any other LS400 model. This means that the sequence used for this particular year is not used in ANY other year, so trying the 1998-2000 or 1995-1996 sequences will not work.
- The 1997 LS400 also uses a different transponder key than any other LS400 model.
- There is a maximum amount of keys that can be programmed onto a 1997 LS400. If this max is reached, you will not be able to pair a new key without erasing the previous keys. Luckily it's simple and all you need is one master key. According to some old threads I've seen, some people have tried pairing a new key to their cars but weren't able to.

So the actual process to pair a new key:

PROGRAMMING A NEW KEY:
1) Get into the car and sit in the Drivers seat, make sure there is no key in the ignition lock.
2) Close all doors, do not lock them.
3) Insert the already programmed master key into the ignition.
4) Turn the ignition switch from "Lock" to "ON" 5 times, very fast. (Leave the key on the "ON" position on the 5th time.)
NOTE: If you turn it 6 times and leave it on the "ON" position the 6th time, I do not believe it will work.
5) Open and close the door 6 times, very fast. (Leaving the door CLOSED on the 6th time, do not open the door a 7th time)
6) Remove the master key from the ignition
7) Insert the new key and turn it "ON", immediately after removing the previous key.
8) Leave the key in the ignition for 1-2 minutes. According to the manual, the anti-theft light should go out after 2 minutes (when it is paired).*
9) Remove the key, open and close the door 1 time. The key should now be programmed to your ECU.

* Note - this did not happen with my car. My security light is working, but whenever I put in a master key in the car, the light turns off regardless if it has been paired with the car. In any case, the process above worked for me.

Now, what if you've tried this a million times and it doesn't work? Apparently, you can clear all of the keys except the one master key you have. The process to erase transponder keys on a 1997 Lexus LS400 is below:

1) Get into the car and sit in the Drivers seat, make sure there is no key in the ignition lock.
2) Close all doors, do not lock them.
3) Insert the already programmed master key into the ignition.
4) Turn the ignition switch from "Lock" to "ON" 6 times, very fast. (Leave the key on the "ON" position on the 6th time.)
NOTE: If you turn it 7 times and leave it on the "ON" position the 7th time, I do not believe it will work.
5) Open and close the door 7 times, very fast. (Leaving the door CLOSED on the 7th time, do not open the door an 8th time)
6) Remove the master key from the ignition. Remove the master key from the ignition switch. All other keys should now be cleared.

If you want to know who I used for my keys, I got them cut by this guy, he was able to do it from a picture I took with my phone.

https://www.ebay.com/itm/153100374854
@1010keys on eBay
Less than $25 and a couple of minutes and I finally had some new master keys.

Anyway, just wanted to share and hopefully help someone who has this specific model. I'm looking to get a new remote paired soon but so I will likely update this post with that process in the future.