First of all, I have a 1999 Ford Explorer with a 4.0L EFI OHV engine, XLS model. Well, my oil pressure on my stock gauge is gone to zero. I am hoping that it is the oil pressure sending unit that is malfunctioning. Well, I've done my research. It should be located right under the power steering pump on the driver side. I have a mechanical oil pressure tester, and a new sending unit. I also have my haynes manual, but the picture given is so close up that it doesn't really help. I tried looking for it for about an hour, but I just can't seem to locate it. Once I know where it is, this should be a simple job. Can anyone help me with this? I want to test to make sure that it is the oil pressure sending unit before I take it to the mechanics to have the oil pump replaced. (Fingers crossed!!!) If someone has the same engine as mine, and know where your oil pressure sensor is located, could you perhaps take a picture of it and post it (both far away and close up shots)? Or could someone with a parts diagram also post this information? I would be very thankful. Thanks.