Oil Pressure Gauge Points at Speedo.

[crankyjew2d2]

Howdy all-

Hoping you can provide me some guidance. After searching forums I've found similar issues but none like mine.

04 Sport Trac, 4.0 motor. My oil pressure dummy gauge points at the speedo most of the time. When I start the truck, the gauge always moves. Or, sometimes, it "quivers," like it's trying to actuate. Rarely, it goes from "Zero" to right in the middle, like it's supposed to. Most of the time, it points wherever it damn well pleases. Always, once the engine is up and running, the needle doesn't move, wherever it's landed. It doesn't vibrate, or bounce around.

I've replaced the oil pressure switch, no change. I have oil pressure; no lifter noise on startup, no bad noises or smells or lights on.

What should my next course of action be?

 

[adsm08]

Next step is to suspect a faulty cluster and install an aftermarket mechanical gauge.

 

[crankyjew2d2]

yeah. faulty gauge/cluster had me worried.

Is it possible to rebuild/replace the oem oil gauge?

 

[crankyjew2d2]

Update, sort of:

It's warmer out now, I've since done an oil change. Oil gauge acts exactly the same.

Seems to be, as stated, an electrical issue. Maybe a bad ground somewhere.

Can anyone provide me some specs/ theory of operation for the gauge?
Hoping for:
If I test voltage at the oil pressure switch, what should I see?
How can I test the gauge itself for proper operation? what makes it go to the middle? ground, or voltage?

thanks everyone