Every so often, particularly during the wet winter months, your distributor cap may be responsible for your no-start problems in your car. Therefore, before you call your Seattle auto body shop, save a little unnecessary effort by familiarizing yourself with your distributor cap and learning how to check it for problems that may prevent your engine from starting up.
First off, you need to know where to find the distributor cap. This is a fairly easy task, because all of your spark plugs should be connected to it. If you’re having trouble, locate a spark plug and follow the wire it’s attached to until you reach the epicenter of all of your spark plug connections. This is your distributor cap.
When you find the distributor cap, inspect its condition. Is it cracked, loose, or scored with carbon? Any of these could allow moisture inside the distributor, which can send your car’s electrical current haphazardly throughout the engine instead of into the spark plugs. This may be the reason your car isn’t starting.
http://www.howtodothings.com/automotive/how-to-check-the-distributor-cap
http://autorepair.about.com/od/troubleshooting/a/ts_no-start_2.htm