Oil pressure sender (RPO) question

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Joined
Mar 15, 2020
Messages
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Location
Utah
My Car
1971 Mustang Mach 1
Doing some wire cleanup and chased some wires to to the oil pressure sender. It has an ignition hot going to a switch in the cab and then out to the sender. Any idea why this was done?

Ask trying to track down origins wire location. Around same spot near firewall; I have a 2 pin not hooked up and a 4 pin flat that was cut. Can’t seem to find what these are for. Same block of wires has 2 pin to transmission - guessing reverse lights.

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Non-tach dash 7123s have a CRANK-only (proof out) signal for the oil pressure indicator lamp, which may explain your hot line.

The 4 pin flat plug is your engine gauge feed harness: oil pressure, water temperature, coil, and carb anti-stall line.

A blue plug with only 2 wires but square like it should have 4 pins is for your seat belt warning system; a black plug with all four wires that is square is your neutral safety switch/backup light plug.

 
Car does have a tach but it’s not working. None of the gauges work except for speedometer (another issue

, it’s 10 mph fast).

Bought some electrical manuals - just taking a while to read it. Appreciate the info - I’ll keep plugging away.

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Here is what I have currently

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Thinking of buying this online but unsure what wire goes where.

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Is there a good color coded book I should purchase?

Ones from Jim Osborn are decent to look at but not helping me much.

Thanks in advance

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red/green goes to coil

white/red goes to oil pressure

red/white goes to water temperature.

 
Am I good to just leave the oil sender unplugged (and drive the car) till I can figure out the dash wiring? I’d just for gauge (which I have a tach), I don’t get why they hooked it to a switch.

 
Am I good to just leave the oil sender unplugged (and drive the car)  till I can figure out the dash wiring? I’d just for gauge (which I have a tach), I don’t get why they hooked it to a switch.
Personally, I would NOT drive the car until I got the wiring straightened out.  You may not have indication of no oil pressure without knowing it.  That's a $6k engine bill right there...

 
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