Join Date: Jul 2003
Location: Smokin melb's eastern suburbs
Being in australia I can really only guess because I have never worked on one of these cars. The tool you are refering to I have always called a test light. I do aplogise if I don't using the right terms in this post, I know how they work but not the exact names, etc!
Relays can be tested, there will be 2 pins that have a small 12v DC charge run across them to activate the 'switch' part of the relay, the points are usually on opposite sides of the relay (may be a pin in between), may be different colored to the other 2 or 3 pins, both face in the same direction and one of the wires will be a ground.
If you put power on these 2 pins you should hear a noticeable click (make 100% sure you have positive and negitave around the right way), if no click is heard its probably cactus. If your not sure which pin is which, take it to an auto elec. I don't reckon they would even charge you to test it.
Your headlights still working seems to indicate this relay, or something related to it, is cactus.
Just like a Tsunami.