What type of diagnostic tester do you need for a 1994 Chrysler new yorker?

For a 1994 Chrysler New Yorker, you'll need a OBD I diagnostic scanner. Keep in mind that's OBD I, not OBD II. OBD II didn't become standard until 1996. OBD I scanners are less common than OBD II scanners these days, so you might need to search specifically for one that's compatible with older vehicles.

Some general automotive scanners *might* have the OBD I capability, but it's not guaranteed. Check the scanner's specifications carefully to ensure it supports the OBD I protocol used in that year of Chrysler. You might even find that a more specialized Chrysler-specific scanner from that era would be more reliable.