Oil Pressure sending Unit

[KBWoodwgn]

I need to replace mine.. I have a gauge in the dash and under the hood is what appears to be a two prong OPSU...what the stores sell as a replacement seems to be a single prong OPSU to match up to the gauge? the two pronger is for the idiot light...Two pronger is cheaper...looks like I have a two pronger.....but yet I have a gauge that has never worked in the 2 years I have owned the jeep. In short anyone know which one I realy need?

[SoCalCruiser]

My '90 takes a 1 prong unit. I think my '89 does also.

Craig

[Brown Bear]

I have a two prong on my 84, it's easy enough to check, the pressure unit is behind the alt, on the block. Should have a big black plastic cap with 2 red wires going out of it. Actually, i think the second wire on all of these jeeps was for the electric choke on the carb, not the idiot light. The EEs at jeep, in their ineffible wisdom wired in a neat little trick, if the oil pressure went caputsky, it would cut the power to the choke, thereby slamming it shut, thereby shutting the engine off....doesn't always work, but it's the thought that counts. So you will probably need the 2 pronger if you're running an electric choke, unless the 1 pronger has 2 wires coming out of it as well, then you can completely disregard everything above this line smile.gif

[bvibert]

AFAIK there should be two down there. A one pronger for the gauge and a two pronger for the choke. All the AMC V8s that I've looked at have been that way...

[Bob Barry]

To second Brian's point:

The '79 and up 360's used two senders.

1) A one-terminal for the oil-pressure gauge; there is no idiot light for oil-pressure on our trucks. Pull the wire to see if you have a spade-type terminal or stud-type terminal on there; they'll ask you which one you want when you order it.

2) A two-terminal switch for the choke. It prevents the choke from receiving current, and thus from heating up, until the engine is actually running. Otherwise, as soon as you turned the ignition to on, the choke would start to heat up and open up. Cutting the power to the choke would not cause the coil to cool down quickly enough to slam the choke plate shut, thus killing the engine. Your engine will happily run on and on if you lost all oil-pressure.

You could use this switch, however, to engergize a relay that supplies power to your coil, so that the coil would not receive power until your oil-pressure was up, and your ignition would cut out if it dipped too low.

[KBWoodwgn]

Ok so that explains why my gauge has never worked but my choke did...I need to replace both... I know the two pronger is behind the Alternator kind of above the oil filter...where is the single pronger?

[mechanic58]

MY 89' has two switches on the oil pressure port..one is a three prong NO or NC type of switch and the other is a single prong reostat type...for a gauge.

[SoCalCruiser]

Am I missing something here? I have the oil pressure sending unit in my hand. I just took it off the '90 so I could hook up a mechanical gauge. It has only 1 electrical connection on the end.

Craig

[porchpiggy]

My 88 GW has both units in line, the gauge unit first and then the choke unit second.

[Bob Barry]

No; you're looking at the 1-terminal oil-pressure switch that we've been talking about.

To KBWoodwgn: The oil-pressure switch is screwed in horizontally behind the 2-terminal switch. It's easiest to change when the oil-filter is removed.

[Merc69]

OK I have a question: What is that switch located behind the oil filter, the 2 prong unit? In the process of having my motor rebuilt that switch is not there.

What is it called? All the books I have seem to skip over this little matter.

Thanks guys

[Bob Barry]

Originally posted by Merc69:
OK I have a question: What is that switch located behind the oil filter, the 2 prong unit? In the process of having my motor rebuilt that switch is not there.

What is it called?It could be called an oil-pressure switch, or choke cutoff switch. It does the following:

2) A two-terminal switch for the choke. It prevents the choke from receiving current, and thus from heating up, until the engine is actually running. Otherwise, as soon as you turned the ignition to on, the choke would start to heat up and open up.

[bvibert]

The description on the Advance Auto Parts web site is Oil Pressure Switch. The part number they list for my truck looks like a three prong one though :confused: GP Sorensen PN: OPS55

[Merc69]

Thanks Bob and Brian, the two Jeep stealerships I called in the area did not have a clue.

Got one on the way, finally