Re: Switchbox Help!
Hopefully you have a timing light, or know somebody that does. You can check each plug wire in turn to see if it's firing. If the sparkplug sparks, the light will flash. There are six basic components in the ignition system.
The stator makes the electricity and three are working, so you know the stator works.
The trigger tells the switchbox when and where to fire. It operates in pairs and you would have to have two bad cylinders to look further into that. Since only one is a problem, it's not the trigger.
The ignition switch kills the spark on all of them and we can eliminate that as a possibility too.
The sparkplugs obviously do the sparking. Easy enough to check that. Swap positions and see if the problem travels with the sparkplug.
The coils boost the electricity to the sparkplugs and you can test the suspected bad one just like the sparkplugs by swapping positions.
That leaves us with the switchbox. If all of the above check out okay, it is logical to assume that the switchbox is the problem. But don't asume that a wire isn't broken or a ground connection is bad. Check those before spending the big bucks on a new switchbox.
You probably don't have a DVA Multimeter or a Peak Reading Adapter. It might be wise to invest in one, but may I suggest that you take it to a Mercury dealer to be diagnosed. Ignition parts can't be returned (unless they are defective) and if it turns out that the switchbox isn't the problem, you're out over $200. I can diagnose a bad switchbox and install a new one in an hour or less (usually less). It might be worth that hour's labor charge to insure you don't gamble over $200 on a part that you might not need.
