2004 chrysler town and country won't start after replacing ecm - does the key need to be reprogrammed?

I don't know what the supplier calls 'pre programmed' but that can not be done. The ECM must be programmed with your cut key with the transponder in it. After installation. It's no wonder it won't start. Now the shifting thing, I saw your other post and those guys both know what they are talking about

I wondered about that as well. I checked with the companuy I purchased the ecm from and they said some vehicles had to be done that way but not the 2004 T&C.

The other strange thing is that when I put the old ecm back in, it is doing the exact same thing.

That's because you took it out and it lost it's memory. I do not understand how they can claim that. The key in a '04 T&C has a transponder.

You can get a preprogrammed unit if you supply the vin # at time of purchase.