Another Wire Question - Oil Pressure

[PeteA216]

Hi guys... The 350 that I'm in the process of putting into my 84 Caprice doesn't have the place for the oil pressure sending unit near the filter. Instead it's by the distributor just behind the intake manifold. The sending unit from the original engine doesn't fit into that plug, so I'm gonna have to use the one that came with the 350. Now this sending unit had only one lead while the original one out of the caprice had two. The plug that connects to that sending unit in the car has three wires coming out of it. My question is why three wires and will I be able to make it work using this single lead sending unit? Could I just splice all three wires into one? As most of you probably already know the car no longer has an ECM or any of it's components. Thanks in advance, you've all been a great help to me for quite some time now.

[silicon212]

You can get a "T" fitting or an angle fitting to allow use of the original switch. On my car, there is a 2-terminal switch in the area to the right of and below the distributor, while the sending unit for the gauge is on the side above the oil filter. They make the pieces you need to adapt one to the other.

[PeteA216]

Is there any way I can use the single lead sending unit (switch) or is that a no go? Also whats the purpose for the multi-lead sending unit? ECM?

[PeteA216]

I just got done studying my Hanes manual. I see the oil pressure switch in the scematic for the "guage, indicator, and engine warning systems", but it says theres only 1 wire for all years. I don't even see a purpose for 2 wires in the wiring diagram. In the ECM wiring scematic I don't see the oil pressure switch at all.

[silicon212]

Originally Posted by PeteA216

I just got done studying my Hanes manual. I see the oil pressure switch in the scematic for the "guage, indicator, and engine warning systems", but it says theres only 1 wire for all years. I don't even see a purpose for 2 wires in the wiring diagram. In the ECM wiring scematic I don't see the oil pressure switch at all.

My car also has the two wire setup on the switch and one of those wires was cut for three years and I never had any problem with it. You wouldn't have even known.

I can see a 3-terminal switch on a car with EFI (electric fuel pump), but this I honestly can't tell you.

[Blue Bowtie]

What year is the car in question?

Car which used three wires on the oil pressure unit typically had one lead for the gauge, and two for the auxiliary switch in the fuel pump circuit. I'd advise that you NOT splice all three wires together.

[PeteA216]

I'm not going to splice anything unless all the wires do the exact same thing.... the car's an '84 sedan that originally came with a 305. It's odd because it's three wires, but only two leads coming from the switch.

[PeteA216]

Well I brought both switches to Advance Auto Parts, and they brought out this HUGE book, and found me a switch with the same base as the 350's switch and the same 2-lead plug as the original switch, so now I have no problem hooking the oil pressure switch.