Audio Systems: car audio for 1981 Mercedes Benz, 4 ohms, memory backup

Question
Hello, i dont know if you can help me or not.... let me start off by saying i dont know a thing about cars but i know just a little about electronics and what not.... i want to install a car radio in my car and i dont have any manuals for my car.. i dont have a radio brand in mind yet but whatever i get its most likely going to be new. i have examined this broken car radio that i have that is fairly new andi just cant figure out how i would go about connecting it... keep in mind the radio i examined is not the radio im going to instal i am just trying to figure out how to do it ...... if you could provide me with a small walkthrough or possibly some pointers or tips that would be great... any information you could give me would be appreciated.... thank you for taking your time to read this...

                       -Blaine  

Answer
Hi Blaine,

This is a process you will need a multimeter for.

With the keys out of the ignition, Test for +12V on all the wires. One should have +12V, (this will be Batt or memory backup). Now turn ignition ON & test all remaining wires. One of these will now also have +12V (this will be ACC) Turn headlights ON & test remaining wires for voltage (this will be ILLUM) - With remaining wires check for continuity. There will be 2 wires for each speaker and when you have a correct pair, you will have a reading of 3 - 4 Ohms. Once established tape each pair together so you they don't get mixed up with other pairs or other wires. Then check continuity with the frame of the car - The wire that has continuity (approx 0 ohms) will be GND.

Test each pair of speaker wires with a 1.5V battery to hear a sound from a speaker. Take note of which speaker is making sound.

Now connect the stereo with the wires you have identified.


Regards Baily :)