I ran into the following information while researching the "out of gas with five gallons in the tank" thread ( https://www.clublexus.com/forums/gs-...ml#post9599253 ) in an online service manual for a 1999 RX300. I don't even know if it works, and I've never seen it before, but, if it helps anyone to program a key without having the diagnostic software or having to go to the dealer to get the job done, then that's a good thing.

The first section is called "New transponder key code" and says that it's for programming keys after installing a new ECU. I've labeled the pages 1, 2 & 3 at the top. Some of the steps here use only the accelerator and brake pedal for programming.

The second section is probably more interesting. It's not been clear to me whether Lexus keys are cut uniquely, or whether the ECU decides whether a key should "work" based on that key's registration with the ECU. This article doesn't seem to distinguish between programming a key to lock and unlock doors, and working in the ignition, i.e. "starting the vehicle." The implication is that a "master key" should do both which might make this procedure useful if one has lost all of their master keys, and especially useful if one only has one master key and has been avoiding getting a second, back-up key made by the dealer do to the cost. What the article(s) refer to as a "sub-key" is the so-called valet key. In a GS (and others) you can press the button between the trunk and gas cap openers to lock them so that someone using the sub-key cannot either put gas in the vehicle or open the trunk. The sub-key will only operate the door locks and the ignition. If the vehicle has a locking console or glove box, the sub-key/valet key won't open them up either. Only a master key can unlock the button between the gas cap release and trunk release.

Let me know if any of this stuff works! And post your personal experiences.

 

You realize the chip is in the fob not the key right? You can get any key that fits in your ignition and put the fob near your ignition swich (obviously a fob that is already programmed) and it will start.

 

I knew the chip and transmitter were in the fob. What I wasn't sure was whether any keys were specifically cut to fit a particular vehicle or not. You've cleared that up, thank you!

 

The OEM keys have the transponder in the removable fob. What about aftermarket? I have 2 cut keys that have a sealed head.

 

Aftermarket, you can buy a number of different kinds of keys; what you want, of course, is a key that is identical to your original master key. My 98 GS400 has three buttons, one to open the doors, one to open the trunk, and one that does double duty, locking the car - and if pushed twice also turning off the lights when they're on auto - and a panic button that triggers the alarm. My 2005 RX330 had a different arrangement where one of the buttons opened or closed the hatchback. If you're using a key that has no buttons, this would be a "valet" key, also called a secondary key, if I remember correctly, which will open the doors when used manually, and start the car, but not open up the glove box (if keyed), or allow the user to open the trunk or gas cap (if they've been locked out by pushing the keyed button between them on my '98).

The "heads" are never sealed, or it wouldn't be possible to replace the battery when it has run down. If by "sealed" you mean "no buttons," then that's a valet key.

 

If it is the same transponder, how would it know it is a valet key unless I program it that way?
A sealed head does not have a battery. The transponder is passive. (or has it's own battery which lasts a stupid long time. )

Unless you meant replacing the battery for the purpose of the keyless commands.

I have 2 cut sealed keys and cannot get them programed. Most of this is me trying to figure out why without paying a large fee.

 

Probably does not have the chip. Where did you buy them?

 

FeeBay. I am not sure if I can even get into programing mode, though. The keys may be fine.

I am going to try the process again tomorrow.

 

Im guessing you just have a key nothing else so you will never be able to program it. Did whoever sold it to you claim it had a chip?

 

Yes. The seller said they have transponders in them.

 

I can confirm that re-programming a Master key and a Valet key does in fact work using the steps described in the op.
I did the 2jzgte conversion from a 2000 Aristo to my 2000 GS300 last year (also engine ecu changed to 2JZGTE ecu) and I couldn't start the engine due to different codes in transponder to ecu.

I had the master key from the 2jzgte but obviously that would not work in my ignition barrel because of the different grooves and it would not work with my keyless/ central locking system.
I had my master key from my GS300 that worked on the keyless/central locking system and the ignition barrel but would not talk to the 2jzgte ecu.

So I followed the steps described in the op, to use the code that is stored on the 2jzgte master key to copy over to my gs300 master key and valet key. And now my gs300 keys fully work with all systems on my car.

Both the master and valet keys have transponders in them if your car came out with an ecu with immobilizer system. The transponder communicates to the amplifier ring around the ignition barrel and then sends a request to the ecu to allow or decline engine start. This is separate to the central locking system which you program separately.

 

This program guide is for the GS300 (97 -05) and is probably an easier way of looking at the steps but is pretty much the same is the op's one.

 

After you remove the master after hitting the gas and brake pedals, does the security light start blinking THEN or only when you insert a blank key?
When you depress the pedals, do you floor them?

This guide is not written as well as one would think.

 

According to the guide:

-Insert programmed black key into ignition switch.
-Within 15 seconds: Press and release accelerator pedal 5 times.
-Within 20 seconds: Press and release brake pedal 6 times.
-Remove black key.
-Within 10 seconds: Insert black key to be programmed into ignition switch.
-Within 10 seconds: Press and release accelerator pedal once.
-Immobilizer warning lamp will flash.
-After 1 minute immobilizer warning lamp will extinguish.

So it should only flash after you have finished pressing/releasing accelerator pedal once.
Yes the GS300 is using a pedal position sensor on the acc pedal so I'm pretty sure you must go all the way down each time. As for the brake pedal, its just a brake switch on there so I don't think you need to go down all the way.

 

This is the video on programming new remote and immobiliers on the second Gen GS. Also works for the first Gen IS.
(The guy that made the video is really active on the forum.)

Using the above method requires healthy door actuators or else it will fail.
Without healthy actuators you follow this method.

There are master and valet key shanks and immobilizers.
The valet key shanks has an extra piece on the tip that prevents it from inserting into the lock by e-brake, glove box and trunk. It will only open doors.

The master immobilizer will turn off security light immediately when inserted into ignition, valet immobilizer will blink once or twice before stop blinking.
You cannot program new immobilizers with the immobilizer on a valet key, must have the master key's immobilizer to do so.
You can however reprogram a valet key immobilizer as a master key, but must have the master key to do so.

There are 4 memory slots for remote, and 6 memory slots for immobilizers (4 master 2 valet)
They go by first in, first out. So if you program a new one in, it will bump the oldest one out of memory.

There are 2 frequency that the GS uses, the US and Taiwan market uses 314mhz, The European/AU market uses 433mhz.
There are aftermarket ones out there that comes with aftermarket remote and immobilizers. Make sure you verify with the vendor that it has the 4C immobilizer chip and the correct market remote for your car.
http://www.ebay.com/itm/252491618185...84.m1562.l2649