Wife's 7.3 oil light comes on and stays on and shows no oil pressure....then jumps to normal range and light goes out. Would it be the sending unit? Or maybe the connection? Where is it located?

Thanks!

 

Probably the sending switch going south, but may be something else. The sending unit for our oil pressure is just a switch. It shows normal pressure at anything above 7 psi, and nothing at pressures under 7 psi. Also, it's not tied to the PCM at all. It's just a direct feed to the dash gauge.

Another thing to keep in mind, it takes the pressure reading from the HPOP resivoir. The bottom end of the engine has about 20 psi more than the HPOP res. Also, if your HPOP res was really at zero pressure, the injectors would not fire. So basically, your engine will quit running before any damage is done to the hard parts of the engine.

The pressure switch is located on the top of the HPOP res cover. If you remove the plastic "Powerstroke" cover to access the HPOP res, you'll see the pressure switch in the cover. It's on the passenger side of the two holes in the res. The driver's side has a plug in it with an allen head.

 

Thanks for the info...now to show my ignorance with this engine! Where exactly would I find the HPOP res cover? And also, could a serpentine belt coming apart take out the sending unit or the wires associated with it?

Thank you for your patience.

 

From the last paragraph of my post above -

A serp belt coming apart shoudln't take anything out associated with the sending unit.

 

I was told that the gauge reads "normal" as long as you have 4 psi of oil pressure. So what is the point of that gauge again?

 

It's basically an idiot light with a needle to make the "savy" shopper feel good thinking he has a real gage and not just an idiot light, while keeping him from going to the dealer to bitch that his truck has less pressure than his neighbor's truck and demanding a warrantee repair.

Ford and others have been doing this for years. Any vehicle that has an oil needle that doesn't move while driving is a fake gauge. I had a guy refuse to buy a Tundra I was selling because on the test drive he noticed the needle moving up & down with RPM, it has a real gauge. To him that indicated an oil problem....and this idiot was the "mechanic" inspecting the truck for the buyer. Manufacturers have figured out that a fake gauge is often better than a real one, and it's cheaper.

 

That so called 'mechanic' is an ignorant fool who knows nothing about cars, trucks or engines.