On my 1994 Mercedes w124 E320 wagon, the instrument cluster panel with the Indicator Lamp symbols that shows warning lights, the symbol Exterior Lamp Failure came on after I pressed the brake pedal. When I first start the engine, none of the warning lights came after starting the engine. Once I first pressed the brake pedal, the exterior lamp failure light came on and stays on, even when I let go of the brake pedal. When I checked the rear brakes lights using a brick to hold down the brake pedal, all brakes lights are working properly. I suspected the brake light switch located behind the brake pedal is faulty. I was under the impression that if the brake light switch is faulty, the rear brake lights will not come on when pressing the brake pedal. Is that true? I checked all the fuses and all of the fuses are ok. Could there be a short electrical wire somewhere? Do I remove the brake light switch and check for resistance using a volt meter? I am somewhat baffled by this issue and does anyone have this problem? Any ideas/comments or helpful hints is greatly appreciated.