Need help to identify my oil sending unit

[danray48]

While wiring my centech harness, I wired my oil pressure gauge according to the wiring directions, and that part is ok. My existing oil sending unit has a place on it for a oil line, but it was solderd shut. The sending unit is a one wire slide on connector, (my gauge does not have a place for a oil line) I wanted a new sending unit, so I ordered one from Morris, for a 79 AMC 258 i6 / 4.2l motor. The one I got is a three prong unit. My wiring harness came with one wire marked "oil". My question is, Is the three prong unit for a mechanical gauge, or the one wire unit? I should clarify, that the old sending unit is screwed in and not part of the brass fitting that has the solderd oil line. Am I making sense? The main question, is does a mechanical oil pressure unit have a 3 prong or a 1 prong connection. I just thought the 3 prong would be for reading resistence. My wiring diagram does not specify which one......Thanks

 

[73CJ]

A mechanical gage will only have a fitting. Like 1/4 NPT.

Pretty sure your stock gage was electrical - one big cluster.

Are you running stock or aftermarket Gage's?

Pics really help too.

 

[csuengr]

Well, there is a oil pressure sender switch, and a oil pressure switch. The three prong one has a switch for the electric choke, and one terminal for the gauge. The gauge switch only tells you if you have oil pressure or not, not how much oil pressure. I bought a replacement for my 1980 from NAPA and used air pressure to tell if it was a switch or actually would tell how much pressure I had. It was a switch. Yep, big can with one terminal on top. I finally gave up and got a gauge and sender from Auto Meter.

And yes, mechanical senders do not have electrical connectors.

 

[BusaDave9]

The OEM gauge is like this:

The harness should be for an OEM Gauge. It screws into the engine on the front left.

It has one connection that goes back to the OEM electrical gauge. The sending unit is grounded as it is screwed into the engine block. The gauge is grounded to the dash.

 

[BusaDave9]

What csuengr is saying is there is a oil pressure sending unit for the gauge. That is what I posted earlier:

and there is a switch that turns on the Oil light
Here are both

 

[csuengr]

There's a light? Forgot about that. Some of those big cans are also switches that just tell you that you have oil pressure. Like GM loves to do.

 

[danray48]

The OEM gauge is like this:

The harness should be for an OEM Gauge. It screws into the engine on the front left.

It has one connection that goes back to the OEM electrical gauge. The sending unit is grounded as it is screwed into the engine block. The gauge is grounded to the dash.

Thanks to all, and Busadave, that can is what I have in there now. I did'nt install the one Morris sent me. I will keep the can in there for now, just to see if it works. Then I should get the manual gauge and run an oil line to the gauge. But you guys answerd my question

 

[danray48]

A mechanical gage will only have a fitting. Like 1/4 NPT.

Pretty sure your stock gage was electrical - one big cluster.

Are you running stock or aftermarket Gage's?

Pics really help too.

I think it's a stock gauge

 

[73CJ]

There is a red light in the main cluster.

The 75 dash I used had a volt and oil pressure gage below as an option.