I have a 1988 300e that seems fine when engine is started (actually there appears to be no drive train issues). All instruments appear to register correctly. However, as soon as the brakes are applied a buzzer sounds (near the headlamp switch) and the instruments return to an off state.
Once the ignition is turned off and allowed to sit for a few minutes then everything registers properly again UNTIL the brakes are applied. Brake lights do not function, brake light bulbs have been replaced.
Can anyone shed some light on what may be happening? All fuses have been tested.
Thanks for any suggestions.
Gerald