There are all kinds of different ohms ballasts. You're right, 5v out is crazy but the 15 in - that's crazy too... Where are you measuring it? Normally (engine running) you've got around 13-14 at the battery adn maybe a little higher at the stud of the alternator. But - with the great Mopar wiring it's ususally down to around 11 at the keyed hot side fo the ballast, and around 8-9 on the coil side. This is normally because of the bulkhead connector. Unless yours is brand new (I'm thinking distinct possibility) it's a good idea to pull the connector appart and clean the male and female sides, and put it together with some dielectric grease. That will minimize the voltage drop accross that connection. You will want to find a ballast with somewhere around .5-.7 ohms. That should knock downt he battery voltage down to around 9v. When a resistor goes bad, it doesnt get more resistance. It simply fails and there's infinate resistance. Otherwise it's good but the ohms are too high.