Oil pressure gauge pegged, and wire unplugged at sending unit...

[jeepthing]

Ok guys, I posted a thread before regarding my oil pressure gauge. Now, with the oil pressure sending unit wire unplugged and dangling, when I either turn the key to accessory or start the car and run it, the oil pressure gauge is pegged max.

It seems that when I actually plug the wire on it doesn't peg, but goes to zero...it doesn't move from there, just sits at zero all the time.

Any ideas.... Is that the default state of the gauge with the wire unplugged? Did I maybe get the wrong sending unit... maybe the dummy light version or something?

Not sure...

[mechanic58]

Assuming your gauge goes to zero when the key's off...the wire that leads from your sending unit to the gauge is shorted out somewhere. You can bank on it.

[jeepthing]

What's the best way to locate the short?

I do know that the place where it joins up with other wires about 6 inches from the oil sending unit, the corrugated plastic wrapped around the whole bunch is melted in one spot...looks like a clean melt like it was up against the manifold or something else. Possible in that area it might be messed up.

Also, would it make sense then that when I plug back into the sending unit the gauge goes back to zero if there is a short? Or is the process of me moving the wire and plugging it back in probably temporarily removing the short..

I'll check it out again tomorrow.

[talntar]

i would check that whole melted area and make sure you dont have a fire waiting to happen.good poss. that is where your problem is but good chance that is not the only wire melted,it has to short on something.

[andy d]

i got that rats nest tied back away from the exhaust with a piece of pot warp looped around the ac hoses. its not very pretty but it works. and i love using stuff i find washed up on the beach smile.gif

[lgrjeep]

On a late model 86 and later for sure the default reading with the sending unit wire "open" is "pegged". Just went through this on a j10, If the wire was grounded (fully) you would get a zero reading. Temp in at the end of the sending unit wire a resistor of some type, sometimes a test light will work or try a heater blower resistor ground the other end of the test unit and see what you get. If the gauge works, replace the sending unit.

[Elliott]

Those things are little better then worthless anyway, go hydraulic and run a decent line to the gauge that will flex with the motor rocking to torque and won't melt. Always carry something to cap the sending unit off just incase you blow the line somehow... or 'ya won't be driving out.
jes my .02