I have a '91 Delica van, which has a large radio/tape head unit. This stopped working, and I have had no luck in getting it fixed, or finding a direct replacement.
So I bought a standard generic CD/radio head unit & fitted it myself.
With the help of a multimeter i was able to identify most of the wires on the vehicle loom, I tested them all for voltage, found 1 that was permanently live, then 1 that was live only when the key was on. Then I tested them all for earth continuity, and found one that showed no resistance to earth.
I hooked up the radio, everything worked OK, but when I turned on the vehicle sidelights, the fuse for these blew. To cut a long story short, I found that the wire which I thought was earth actually carried voltage, was the live feed for lights, horn, etc.
What's going on here? Was my earth testing faulty? I can't find any other earth wiring, in the looms that connect to the radio, so I assume the factory fitted radio is earthed only through its chassis connection.
Is this an example of a floating earth?