trouble shooting oil pressure guage

[Sitting Bull]

My oil pressure guage went kaput, no real reason except that it is all rednecked together probably. I'm going to be replacing it with an autometer guage, but I would like to get this one going until the order shows up.

I've spent some time trouble shooting it this morning, and I think the sending unit itself is bad. Doesn't surprise me since it is "new".

When playing around with the test light (while the engine is on), I noticed there is power going to the sender on one of two wires going into the top of it. But no power coming out of the sender (the purple wire that fits on the nipple). I'm assuming there should be power coming out of the sender nipple while the engine is running???

Since there is power into it, but not out of it, I'm assuming the unit itself is bad. But then again, I don't really know how it works anyway.

Thanks!!!

[Crazy_Jeepman]

I forget the colors of all the wires. However there will be no power to or from the oil pressure sending unit. Your Oil pressure gauge is powered up at the cluster, the sending unit only increases or decreases OHMS as oil pressure changes, I think you would find most all sending units work like this. There is a Oil Pressure Switch that could be supplied 12 Volts with Key on, and will switch the 12 volts to the electric choke when running. I think that is what you are getting the reading from.

[shredby4]

My sender only has ONE wire only. Does yours have the "low pressure" light? What's the other wire connected to?

What's the gauge reading?

Of course the parts store could have sold you a defective part or the wrong part too...

[Sitting Bull]

I forget the colors of all the wires. However there will be no power to or from the oil pressure sending unit. Your Oil pressure gauge is powered up at the cluster, the sending unit only increases or decreases OHMS as oil pressure changes, I think you would find most all sending units work like this. There is a Oil Pressure Switch that could be supplied 12 Volts with Key on, and will switch the 12 volts to the electric choke when running. I think that is what you are getting the reading from.

As always, thanks for the help Pete. I save more time and money by posting these questions than I can imagine.

PS - I'm ordering my Autometers as soon as I get done here. Y'all talked me into them last night!

[J4GRAND]

My sender only has ONE wire only. Does yours have the "low pressure" light? What's the other wire connected to?

The 2 wire set up is used on rigs with an electric choke.

[Crazy_Jeepman]

As always, thanks for the help Pete. I save more time and money by posting these questions than I can imagine.

PS - I'm ordering my Autometers as soon as I get done here. Y'all talked me into them last night!

Hey no problem! By the way YoungJeeper is going to ask you a favor next time he see's you

[shimniok]

My 86 has a switch and a sender. The sender is one wire as was the one on my 85 when I had it. The switch has multiple tabs and it enables the choke when the engine is running.

The sender is just a variable resistance and presumably the gauge cluster measures voltage drop across the sender.

IIWY I'd measure resistance across the sender with the motor off and with it idling. Measure from the tab to the engine block or some other ground. Maybe even have someone tap the gas a couple times to see if the resistance changes at the higher rpms.

Michael

[Sitting Bull]

Hey no problem! By the way YoungJeeper is going to ask you a favor next time he see's you

I'll be heading over there next Saturday...I can hardly wait to see what it is...

[Crazy_Jeepman]

I'll be heading over there next Saturday...I can hardly wait to see what it is...