I have a 2005 LS430; this morning the ignition was locked and neither a smart key nor regular key could unlock it. I noticed that the key fob would not lock or unlock the doors. On my smart key the light comes on when I push the lock/unlock buttons.

1. Close all the vehicle doors.
2. Insert the ignition key into the ignition lock cylinder.
3. Press and hold the door unlock switch.
4. While holding the door lock switch in the unlock position, cycle the ignition ON, OFF, ON, OFF.
5. Release the door unlock switch.

thats how key entry works as to fob -dead battery--failure

do you have remote start needs different programming then simple lock unlock and most locksmiths dont have that programming also is the for actually for your vehicle if have regular lock unlock below is how to program also when battery changed need to reprogram fob How to reprogram my Honda key fob insert the key into the ignition and turn the key to the "on" position. Press and hold either the "lock" or "unlock" button on the remote for one second. Release the button on the remote and turn the key in the ignition to the "off" position. Repeat this process two additional times.

Transmitter Programming Procedure
Close all the vehicle doors.
Insert the ignition key into the ignition lock cylinder.
Press and hold the door unlock switch.
While holding the door lock switch in the unlock position, cycle the ignition ON, OFF, ON, OFF.
Release the door unlock switch. The doors will lock and unlock to confirm the program mode.
Press and hold the LOCK button and the UNLOCK button simultaneously on the transmitter. After a delay of approximately 15 seconds, the doors will lock and unlock to confirm the programming of the transmitter.
Turn the ignition switch to the RUN position in order to exit the keyless entry transmitter mode.
Operate the transmitter functions in order to verify correct system operation.
Good luck

You have to go to a Chevy dealer. They have a hand-held computer they plug into your car to get it into programming mode. Probably cost $50-$60. Call them for an estimate.

Right do a bodge up colin type repair,get a spare key cut without a chip and wire it up under the car in a secret place and grease and wrap the shaft then if the better half locks herself out then at least she can open a door .

you can try this, with the battery connected lock the car using the key fob, make sure no keys are in the ignition. Disconnect the battery again and let it sit for 30 min or so, reconnect the battery and using the key fob unlock the car, it should start, if not repeat the procedure and insert the key into the door lock to unlock the car, both of these solutions should reset the security system. Good luck.

unlock the door then press the lock button on remote and hold down for 20/30 secs.manual does say hold button.....

i would say the theft module saw the door trying to be open without the door lock or fob first, once the door lock button was pushed it shut down, it new doors were trying to be unlocked in a theft manner, once shut down it needs time to reset or needs to see ignition cycle with key and read chip in key, smart system isnt it, good luck.

Sounds to me like the key FOB was swinging on the key change and hitting the column. What you are describling is the door locks cycling and not staying locked because the keys are in the ignition. To see what I mean try locking the doors with the keys in the ignition, they won't stay locked till the key is removed on newer vehicles.