I have short in my 1992 300 se - 1992 Mercedes-Benz Mercedes Benz S Class

If you have installed new components to your car, make sure you are putting together the right polarity of each wiring which is positive to positive and negative to negative from the new component to the wiring harness of your car,
if you are testing for a short circuit , the reading is zero voltage dc
but if open circuit it is infinite when you are using a voltage meter. see manual of your vehicle to see the circuit diagram. then follow the positive sign( +) and that of the negative sign (-). when testing.
always set your meter voltage higher than the voltage produced by your vehicle which is 12vdc standard source.
when you turn on your radio to the best station but still you are hearing some interference or annoying sounds or noise, then something wrong with your connections,
double check the connectors you have connected like the RCA jacks ,auxiliary jacks, try to take them off first then try listening if it is clear sound coming from your radio station.
how did you know you have short circuit in your car??? ehat is your clue??? let me know. and what are the experiences you have encountered to determine exactly what it is