welcome.....
i.found this on another site...
http://www.dieselplace.com/forum/63-...re-switch.html
maybe itll help
It's different on a 6.2 and looks different, so don't go by this picture. It's called pressure switch, but it's the sender for the oil pressure gauge, so not exactly a switch.Anyway, if you take off the air cleaner housing and lay yourself across the middle of the engine, head to the firewall, you should see the vacuum pump on the middle to your left. The pump looks like a pillar (with a driveshaft inside) with a round housing on top (with the diaphragm inside). Now further back and a bit to your right, between the back of the engine and the firewall, there should be a metal cylinder screwed into a fitting down there. The cylinder has a slightly larger diameter on the bottom and should have an electrical contact on top.You can screw that cylinder out, but you'll have to get at it from under the truck where it goes into the fitting: There's a seam between the bottom part that goes into the fitting and the cylindrical housing, and when you start turning the top, the seam won't hold and you end up turning only the top. Once it's out, you can replace it, preferable with a mechanical oil pressure gauge. A mechanical gauge is even cheaper than a new pressure switch.You may have to take off the glow plug relay/controller to get at the pressure switch. If you do so, be aware that one of the large terminals of the relay/controller always has 12V on it, so you might want to disconnect the batteries first.