Abstract: A device for alternate use as an emergency replacement coil and condenser unit or as a tester of automobile spark plugs. The unit is in the form of an enclosed housing in which an automobile ignition coil and condenser are mounted in parallel to the low voltage coil terminals. A momentary normally closed push button switch is mounted in a housing wall and connected in series with one of a pair of low tension lead wires extending from the housing, with the lead wires connected in parallel to the coil and condenser. The high tension outlet connection of the coil is mounted adjacent a hole in the housing for insertion of the coil terminal of cable of an engine leading to the high tension connection of the distributor cap, when the low tension lead wires are connected across the low tension terminals of a defective engine ignition coil to substitute the device for the engine coil.