I did some more research and found that I should have been measuring milliamps not voltage between the battery terminal and the cable. The only thing the voltage showed was that there is a drain on the battery. So I was doing the old fashioned test removing the fuses one by one. About half way through the process I noticed something odd. The ammeter had been reading a steady 4 milliamps since I placed it between the battery and the cable. For no apparent reason the needle began bouncing between 15 and 40 milliamps about every second and as regularly as a ticking clock.Can anyone tell me what's going on and can this help me find the drain. I'd still also like to find a safe source to download manuals for a '81 w123 300sd ( which is the car the post is about). Thanks for any advice. A previous owner has done some extensive messing with the electrical system.