I hope that I can help some, you should still check online or even call the ScanGauge company, they are incredibly helpful. I have used this on Fords from 1995 to 2006. Chrysler Jeep 2011, so it works if you have OBDII which is the same port on your Dodge, so it should work. I would say from my experience that it will work. I love my ScanGauge, just make sure that you unplug it and hide it when you go in for Smog check or they ding you for having something plugged into the "government port," that is what the smog checker said to me.
This should work on all vehicles after 1995 when an electrical diagnostic socket was placed beneath the dash, right of the steering wheel were installed on most vehicles in America. This socket is for the Gen II OBD's (stands for Generation 2 On Board Display) diagnostic monitors and is used by mechanics to read the engine and car codes in the car's ECU (Electronic Control Unit). The ECU stores information on speed, fuel consumption etc and this is what the device taps into.
it will absolutly work on your 04 dakota, your vehicle is equipped with a multitude of senor outputs, u simply plug this gauge in to the OBD2 port (under the dash, looks like a computer terminal) and the gauge will come to life, and automaticaly adjust to the right system to run on your truck. it will display several handy functions automaticly, and if your willing to read the manula(long and complex) instructions, it will display almost anything u want, i use mine for volts, avg fuel economy, water temp, and lots of others. its easy to use after u play with the functions. and if for some reason u get it all set wrong or want to start over, unplug and plug back in, and u have a freah slate. hope this helps.
This will work on any car that has an OBD2 sensor plug which, if I'm not mistaken, is most cars that were built in 1996 and after. Although some cars built before 1996 have the OBD2 sensor plug as well.