What format is the OBD II for a 2003 Voyager? ISO-9141? ALDL? I know Ford uses/used PWM but I am trying to find what Chrysler uses for their Voyager.

didnt know chrysler has a voyager

call the dealer and ask for the service dept. I trick those guys into answering my questions all the time

With the abundance of OBDII scanners on the market, I have to wonder why you want this information. Are you trying to make your own scan tool or something? I've wondered about it myself before at the curiosity level, but don't have a pressing need for it.