Keyless entry program successful but doesn't work
 

1999 RX300

I have one key that has the keyless entry buttons, and one key with no buttons. Both keys work correctly to start the car. However, the keyless entry buttons do not do anything.
I've followed the instructions (available in MANY threads, and other websites) to program the keyless entry key to the car. When programming, it does give the single lock/unlock feedback that the key has been successfully programmed. When I go into the "how many remotes are programed" mode, it indicates that a single remote is programmed. However, none of the buttons on the remote actually do anything.

Possibly related issue: 8/10 times (I cannot 100% reliably reproduce it) when unlocking the car with either key (manually, since the keyless entry doesn't work), the alarm goes off. I frantically get in and turn on the ignition, which turns off the alarm. Also, when unlocking the car with the key, only the driver's door unlocks, not all the doors. Occasionally it will unlock all the doors, but 9/10 it won't.

Has anyone experienced this? Any ideas on how to fix this?

Thanks!

I wish I knew the answer. I would double check battery in remote. I would clear all codes (remove remotes) and wait 24hr and try again. I have two RX300 (2000) and both came with only one valet key each and the alarm has NEVER gone off using the keys. I added a aftermarket remote key ($25) this spring and it took two days of trying the same thing over and over till it worked (wish that was more help). With the alarm thing makes me think it something else, that's why resetting the remote codes might help. The power door locks stick and go out so the other doors not unlocking might not be the key (listen for a noise in the doors). After ten years (same truck) I now know how being able to double tap unlock and HOLD it, rolls down all the window and opens the sunroof before I get to the truck, is amazing for hot weather.

Well, the answer for me was very unsatisfactory, but after about a week, the remote just started working correctly. I have no idea why. It just started working out of the blue.

If it's OEM key that's 21 years old it could have been dirty or sticky button that worked free.
This is one I ordered this spring for $25 having a way to unlock my car that is cheaper than getting another key cut or locksmith. If you don't have a second key, it stops you from locking your key in the car. I just have the fob without having they key part cut.

My bet is that you had a loose connection in one of the latching mechanisms, and that driving around bumped it back to a connection. Anyway, sounds like you got lucky!