Type 53 Relay
 

I opened one up which you can do if careful. Actually these are available at most parts stores except they have another terminal for "normally closed" contact. In an emergency you might be able to open one up and clean or unstick the contacts.

http://forums.pelicanparts.com/uploa...1274275558.jpg

I just replaced all of the ones in my car with new ones from Roger for $5.