pcmhacking.net

Ive got a pretty simple question hopefully someone can answer.
I understand how the VATS system works once the BCM reads the correct key, but how does it actually 'read' the key?
Obviously through the key reader/ring around the ignition barrel. But how does the key contact being connected to that send a signal from the key? What is inside the key that makes the magic happen?

I originally thought the BCM put power on the key reader, and the key would earth through the barrel itself to create a signal. I found I was wrong today when I noticed there is no connection from inside the key to the metal key blade, so that can't be the case. The key blade is not part of the circuit.

I put my multimeter on the key reader and switched the IGN on with the blade only, and can see the BCM seems to be pulsing battery voltage onto the ring.

Also why are they only usable once? Why can't they be reprogrammed to a different car?
Am I correct in saying once a key has been programmed to a particular BCM that key is only going to work with that BCM forever?
How do the locksmiths read keys and create duplicates of them?

So many questions
I'm quite interested
Thanks in advance

Bottom of the kry head is a small round bit of steel. That runs on the ring around the barell. That's how they connect.
The rest is out of my league.

There is a small microcontroller, an EEPROM, a battery, etc. within the key.

Yes, there is a connection to the key blade. From memory, this is via a small wire that is pressed between the case and the blade.

Keys are "one use only" as a design choice in the microcontroller firmware for added security. This is so you can't just take any/your key and re-purpose it to take someone else's car. There's some sort of pre-configuration that's done on a new key to allow it to pair with its intended BCM.

Joe.

Just on this can a worn or old key cause a random stalling issue? Does the key/bcm always need to be in perfect contact to prevent vats kicking in at random times? Or is vats disabled once the car has been started.

Na once it is running the key has no part in keeping it going.

No worries . Thanks for that.

Can you use Tunerpro RT to program a new key?

no you'l need a blank new key and scantool like tech1 or tech2