My 03 3500 is not unlocking all 4 doors when I unlock the doors with the key and when I open the drivers side door the factory alarm goes off until I start the truck. It does not have a remote, just the key. The drivers side opens fine but will not open the others when you turn the key to the left twice. Any ideas? I bought this truck used and just got one key with it, is it possible to get a remote for the keyless entry? THANKS