Re: 4.7 oil pump
The 2004 model WJ isn´t using a pressure transducer anymore, but a low pressure switch (but ofcourse there are always some in between models who are different). You can see the difference at the pressure switch (transducer) connector. When it has two pins, it has a pressure switch, when it has three, it has the transducer.
But most of the times the pressure switch (or transducer) is faulty. Mine also has the pressure switch and it went bad intermittently. Can eventually be a wire problem.