Overvoltage problem, but not the K1

[Finster]

I have a 91 300D, 2.5L. Out of the blue the typical symptoms of a bad OVP occurred....rough idle, ABS light on, and no tach. the fuse on top of the OVP blew. Replaced fuse and blew again. Ordered new OVP with 2 fuses and 1 of the two blew on start up. ABS light is out but rough idle and no tach. After many hours and days of testing and checking components, I'm stumped. Here is what I have: key not in ignition, take neg off the battery then retouch the neg to battery terminal I hear the convenience relays click and there is spark at the the battery terminal...With battery connected, I turn the key to position 1 and still good OVP, but turn the key to position 2 (not starting or engaging the starter and the fuse on the OVP blows. I've disconnected the radio, the CCU to isolate them and the fuse still blows. I've replaced the convenience relays, but no luck. Can anyone offer some advice? I think something has gone to ground, but I don't know what component....