I have a 1993 3.0 v6 ranger ..... it uses an oil level sensor unit.. attached to the side of the oil pan... with a single wire to it.... it measures oil level....not pressure.... look in your haynes manual.... mine triggers the "check engine" light at exactly one quart low.... while the oil pressure gauge shows. full normal pressure.
check and clean the wire... connect to the sensor.... this is not the standard set up ... but was also used on some earler model taraus fords as well... \