Some auto parts stores have a module tester, but it sounds like you've got a bad module. Here's one thing that can happen- - - -an open-circuited spark plug wire can cause the coil high voltage (over 50,000 volts) to fire through the insulation in the coil windings and hit the 12 volt primary winding with a shot of very high voltage. This can cause repeated module failures, often after a very short period of running the engine. Modules just aren't made to handle spark plug voltage. There's no test for an internal arc-through- - - - -all the ohmmeter checks will be normal. If in doubt at all, change the module, coil, and plug wires at the same time. The normal resistance for a plug wire is up to 1,000 ohms per inch, so an 18" wire can have up to 18K ohms of resistance and still be good. Plug wires that measure up into the meg-ohm scale, or show a complete open circuit need to be replaced.
Jerry
