I had a question about that six prong socket on the valve cover when rebuilding my 89 B230FT engine. It was attached to some sort of sensor on the rear right hand side of the engine block in the bell housing section. This was pointed at the flywheel which had what looked like 4 magnetic inserts at 90 degree intervals. What the hell was it? I knew my car had a hall sensor distributor so in was not a firing sensor like on the later models. John Sargent provided the answer and said it was a dealer accessable timing sensor, I would guess to check the camshaft timing to the crankshaft timing. No diagnostics - so sorry.