Here is a question for ya.
When I lock my door with the master key and open the door without the key (ie. with window down, I reach in, manually unlock and open the door) the car SHOULD flash its lights and honk a horn...correct? My 1990 300E does this. My 1994 E420 does not. The lights on the 420 do flash but the horn doesn’t honk. I know the horn does work, and actually I took a meter and there was no voltage coming to it. No fuses are burnt out. Any relays in the rear-most compartment that could be involved in this? Where should I start?