Oil Pressure Gauge Points at Speedo.

[crankyjew]

Howdy all-

First post on this forum. I've had a couple Rangers, now an 04 Sport Trac.

Hoping you can provide me some guidance. I apologize for yet another thread concerning this. After searching forums I've found similar issues but none like mine.

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.

It seems to me like the motor that drives the gauge needs work.

What should my next course of action be?

 

[crankyjew]

Bueller.. bueller..

 

[MidnightRebel07]

Just disconnect that and run a mechanical gauge. I never liked dumby gauges or lights. There's no motor that drives the gauge.

 

[crankyjew]

Thanks for the reply. I know the dummy gauge is pretty lame. But I don't want an aftermarket gauge stuck somewhere on my dash.

I've read about replace the oil pressure sending switch with a mechanical sender, and replace the resistor on the gauge cluster with a jumper, to turn the dummy gauge into an actual reading. That's a definite possibility.

I'm concerned, however, with the actual motion of the needle currently, how it seems to get stuck. The fact that it consistently moves, tells me the signal from the sender switch is good.

If not a small motor, what makes the needle move? There has to be something in the gauge cluster that I can clean/rebuild/adjust, right?

 

[MidnightRebel07]

It's electrical. The whole gauge cluster comes out but I don't think you can clean/ rebuild the individual gauges. It doesn't have an oil Lin going to the gauge like older gauges.

 

[crankyjew]

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

 

[fullmoonrising]

Same thing as mine your over shoot'n the problem. You need to replace the instrument cluster or just deal with it.

 

[crankyjew]

Overshooting, sure. But replacing my whole cluster is my last resort. I would rather fix this one for free than spend the time and money to find a new replacement.

I'm plowing ahead with this goal until it proves fruitless.

I ran the odometer test mode and established that the signal from the oil pressure switch is good. So, again, can anyone provide me specs about how the gauge itself functions? If I apply X volts to X wires, what should happen? I know I've seen this info somewhere, but my searches are only coming up with threads suggesting that I install an aftermarket pressure gauge.

 

[sr139fox]

I remember reading somewhere that the gauge is not an actual gauge. Its more like a fake gauge. It displays if you have oil pressure, not the actual pressure. More like a low oil pressure light, only its a gauge. Have pressure, point half way, not pressure, don't move off low. I looked on this forum and did not see it, unless it is buried in a long post of a different name. Dave P.

 

[crankyjew]

Yep. I understand fully that the oil pressure gauge is actually a dummy gauge. Thanks for the reply and the input.

As soon as I'm feeling ambitious, for lack of any other significant help, I plan on pulling my cluster, pulling it apart and seeing what I can do about this. I strongly suspect the motor that drives the gauge can be tested, cleaned, adjusted, calibrated, etc. I guess I'll just figure it out on the fly.