There aren't any silver bullets. You need, as a minimum, the owner's manual, a multimeter, and some test lead extensions are always handy.

Then you start looking for shorts. Go to http://mb.braingears.com, download the electrical troubleshooting manual and schematics, so you can print out the schematics you need for the suspect circuits.

Your car is 18 years old. Who knows what it's been through. I just spent several hours over the last few days trying to figure out why my backup lights didn't work (results in a nearby thread).

Electrical troubleshooting can be a massive amount of grunt work, and even if you are experienced, bizzare results can sometimes take you down blind alleys.

Duke