Ls400 Key Programme

Yoda400 · May 24, 2015

Found this thread interesting.

One question though - if you buy a used key and transfer the transponder etc into a new blank key will the reprogramming process identified in this thread reprogram the previously programmed transponder?

This is an old thread i'm digging up I know - but does anyone know the answer to Keith's question above?

I've got a key cut and a used transponder. I'm now trying to program the key but haven't had any luck - will keep trying different methods though.

Has anyone got instructions saved on their computer that definately did work on their LS400? I'd be grateful if you could share :)

Mine is a 1999 model

Many thanks in advance chaps :)

Ok quick update as i've now done it - didn't take long!!! I've now tried the methods in this thread and the methods that worked for my 1999 LS400 are below (thanks to Haylands and to dkp). Just to confirm also that a second hand transponder chip does work!:

To program the key so it starts the car:

Requires one working LEXUS Master Key.

1. Enter the car with the existing master key and close all doors.

Simultaneously depress and release both the brake and the accelerator

pedals.

2. Within 5 seconds, insert the existing master key into the ignition.

DO NOT TURN THE KEY.

3. Within 15 seconds of inserting the ignition key, depress and release

the accelerator pedal 5 times.

4. Within 20 seconds, depress and release the brake pedal 6 times and

then remove the existing master key key from the ignition.

5 Within 10 seconds, insert the new key into the ignition.

6. Depress and release the accelerator pedal one time. The security

light should now begin flashing to indicate that the computer is reading

the new key and programming the system.

7. Leave the new key in the ignition for 80 seconds. When the security

light stops flashing the new key is registered, Remove new key and

depress and release brake pedal 1 time. The programming process should

be complete.

8. Test the new key. Place the key into the ignition and verify that the

car will start.

9. If this is a new remote master key, test the remote functions on the

new key.

To program the remote central locking part of the key:

1. Sit in the driver's seat and lock all the doors.

2. Unlock and open the driver's door.

3. Insert the key into the ignition and remove it (don't turn it...just

remove it).

4. Using the MANUAL lock switch on the driver's door, lock and unlock

the door 5 times.

5. Close the door.

6. Open the door.

7. Lock and unlock the driver's door 5 times but this time use the ELECTRIC lock. Insert the key into the ignition and turn

it to the "ON" position. Remove the key. The locks will now cycle by themselves.

If the door locks do not cycle (lock and unlock) by themselves then the car isn’t in programming mode and you must start over.

8. On the remote, press and hold the LOCK and the UNLOCK button at the same time for no more than 2 seconds.

9. On the remote, press the LOCK button for no more than 1 second.

10. Close and open the door to end the programming procedure.

cruisermark · May 24, 2015

good news

i did same as you a few years ago with my mark 4 - it did take be many many tries but it worked in the end - i dont know what it was that made it work in the end

Titch LS · January 9, 2016

On a side not , if the plastic case to your original 3-button key is falling apart due to old age or overuse, just use the solid valet key when starting the car. That key will last forever. The transponder is in the 3 button case right?, so, as long as both keys are on the same key ring the car will start with the never-wear-out valet key. I do this every time now.