A while earlier I wrote about my motor having a NO oil light and SLOW circuit actuation. I bought the software and harness from a guy on EBAY. The wiring harness was advertised as a 10 foot cable but only measured at 6. The only laptops it would interface with were old 9 pin serial port models. My Seloc book gave confusing and contradictory test information on the system. I finally looked the whole thing over and decided the oil pressure switch was defective. I got one for $119.00 and figured how to release the locking mechanism and changed it. It works fine. Just passing this info along, seems the most probable cause for a no oil light is the switch, IMHO. I know it can be the relief valve, the lift pump, or a host of other reasons, but I blocked off the return line and it made it work work so I dive bombed the switch.