I bought a 1999 RX300 a couple of weeks ago. The dealership only had the valet key, as the previous owner had lost both the transmitter keys. I took it back on Saturday and they installed a new ECU and made a new transmitter key. The remote locks work great, but now my security light will not go out. When the system is "armed" it flashes once every half second, but once I unlock the doors and start the ignition, it starts to flash even faster and never stops flashing even while driving! It is really annoying. I'm going to take it back to the dealership but due to my schedule it will be a couple of days before I can get back there. Does anybody know a quick fix? It seems like it's still in a programming mode or something.

 

You're talking about the little red LED, right?

Put a small piece of black electrical tape over it until you take it to the dealer to get it fixed if the light bothers you.