Can't you check continuity of a length of wire? Disconnect all 4. Disconnect the coil + (and the coil -) On the end of the ballast where the two wires are NOT jumpered, ONE of them goes to the coil (HINT!!!! will be the same color!!!) and the other goes to the ECU. Disconnect the ECU. That wire now will not go anywhere and you can check continuity to ground and anywhere else and it will be open.