When I turn on the foglights on my 93 500E the dashboard warning light comes on, and it will go off when the foglights are turned off. All the lights work - verified by two shops (i guess because I don't know what turned on lights look like:rolleyes

One mechanis said he thought it might be a short somewhere.

Any ideas or similar experience with this situation?

If there is a short - what is the best way to trace the short?

Thanks for your help.