I'm working on an 03 gas 2500. Lost the keys. I drilled out the cylinder, removed the old cylinder, and installed a new one that I ordered from the internet. The truck will start and then die as soon as the key is released from the crank position. I know that I need to do some sort of programming on it, but I've tried following various guides I've found on the internet with leaving key on and such, and can't get those to work. Does anyone have a guide on how to reprogram this key? I'm trying to avoid the expense of hauling it to the dealer.

Thanks

 

See a locksmith

 

I'm hoping there's something I can do myself instead of getting a locksmith. That's probably more expensive than the local dealer.

 

it's too bad you replaced it with generic parts instead of matching ones.
You can try this reset procedure and see if it helps:

https://charm.li/Chevy%20Truck/2003/...%20Components/

 

It might be the Passlock system. This is the security system that keeps the engine from running if it doesn't recognize the right key.