Key not working
A while ago my key - integrated key fob 5 buttons died (2008 WK). I tought the batteries died and because I was in a hurry I just grabbed the spare key, replaced the non working one wich I tossed in a drawer. Yesterday I tried to ressurect it, replaced the battery with a new one, and still did not work. I pressed every button to no effect. I craked it open, cleaned contacts, pcb, measured battery voltage, made sure it makes good contact, but still nothing. I noticed that on the PCB there are a loop antenna and a SMD one. I think one is for 434MHz - remote functionality and the other is for communicating with the Ignition ECU module when the key is inserted.
This morning I opened the car with the working key, and I tried cranking with the non working key - it worked! I tried the buttons, they are working too!
Is the module reprogramming the key each time it's inserted? It may explain what happened: The voltage was too low to reliably program it and it failed to work as a remote even when the batteries were changed . Once inserted it recognized the right code and reprogrammed this time right because the voltage was up again.
Is my thinking valid or something else is going on, my key is failing? Can somebody explain what is going on with the key? I'm affraid It will just quit working again.