That's what I suspected, 3 wires, one +12V, one -12V and which pin does the other one go to? My tool does read and reset the ECU so I am fairly sure that once I know where the 3rd one is I can reset the service lamp. That's what I'm trying to find out here. There are many more pins and only 3 are identified (excluding the +/- terminals.) Unless someone with more knowledge can add to this discussion I'm convinced that at least on the 850 series, if not V70Is as well that the under the hood diags were simply rewired/relocated to the RS232 plug under the coin holder. My tool gives the same blink-code sequences as with the 95 and previous owner friendly system.