How does the oil gauge function? Mine is pegged to the right

[MisterB]

My '69 has a brass from the back of the gauge on the dash to the engine. I don't see that on this truck.

I'm trying to troubleshoot why it doesn't work

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[Dmack]

There is an electrical sending unit below the distributor. Make sure the wire is plugged in.

 

[MisterB]

There is an electrical sending unit below the distributor. Make sure the wire is plugged in.

Is this it? Looks like it's missing the wire. I'm not seeing a wire dangling anywhere. Where should I be looking, as far as where the wire comes from?

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[1973c10]

Yep that is the sending unit

is that a copper tube behind the spark plug wires ??

 

[MisterB]

Yep that is the sending unit

is that a copper tube behind the spark plug wires ??

I'm not sure. I'll have to look again. It's kinda hard to reach back there. It's got a 6“ lift and 35" tires. Even on a ladder and with my long arms, it's interesting.

So where should the wire come from that plugs in that sending unit?

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[eskimomann209]

When in doubt. Run a new one. But it’ll be coming off the junction box. Find it there and trace it to its end

 

[73c20jim]

I put rags on both fenders and lay 3 2x4s across the fenders. A little ladder to get up, lay stomach on 2x4s. I can easily get to the distributor area.

 

[MisterB]

When in doubt. Run a new one. But it’ll be coming off the junction box. Find it there and trace it to its end

I decided to just go ahead and buy a new oil pressure switch. They don't cost much, and it sounds like they can definitely go out. Replacement looks easy enough.

I've got doubts on how to wire this though. I can't find any wires dangling anywhere or that don't have a proper place. Can I just run a 12 volt power supply from anywhere that turns on with the key, and call it a day? Or, do I need to specifically find the proper place in the junction box and run it from there?

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[C10MixMaster]

I decided to just go ahead and buy a new oil pressure switch. They don't cost much, and it sounds like they can definitely go out. Replacement looks easy enough.

I've got doubts on how to wire this though. I can't find any wires dangling anywhere or that don't have a proper place. Can I just run a 12 volt power supply from anywhere that turns on with the key, and call it a day? Or, do I need to specifically find the proper place in the junction box and run it from there?

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if you run 12 volts to the sending unit nothing good will happen, dont do it lol. The sending unit acts as a variable ground for the gauge so puting 12 volts directly to it will fry it. Start at the junction block look for a dark blue wire that should be your oil sender wire. The gauge pegged to the right would indicate its grounded.

(Edit looks like my cheat sheet was off after reviewing some schematics looks like tan is the color for oil pressure gauge)

 

[Matt69olds]

If the truck is a 69 I think those have mechanical pressure gauges....correct? If so, remove the electrical sending unit, and plumb the copper tube to the oil pressure port behind the distributor. If it’s an electrical gauge (which sounds like it is, a mechanical gauge unhookeded should read zero oil pressure, an electrical gauge will read pegged past 60) find the tan wire coming out of the bulkhead. If you ground the wire, the gauge should read zero.

 

[MisterB]

If the truck is a 69 I think those have mechanical pressure gauges....correct? If so, remove the electrical sending unit, and plumb the copper tube to the oil pressure port behind the distributor. If it’s an electrical gauge (which sounds like it is, a mechanical gauge unhookeded should read zero oil pressure, an electrical gauge will read pegged past 60) find the tan wire coming out of the bulkhead. If you ground the wire, the gauge should read zero.

No, I have a 69 and an 80. The truck I'm having the issue with is the 80

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[chengny]

I've got doubts on how to wire this though. I can't find any wires dangling anywhere or that don't have a proper place.

Or, do I need to specifically find the proper place in the junction box and run it from there?

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As noted above look for a tan wire. It also can be identified by the special boot over the connector. The lead is offset from the center of the boot:

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If you can't find the tan lead and need to run a new one from the firewall, it will originate at the D6 socket as shown in the image below:

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[MisterB]

As noted above look for a tan wire. It also can be identified by the special boot over the connector. The lead is offset from the center of the boot:

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If you can't find the tan lead and need to run a new one from the firewall, it will originate at the D6 socket as shown in the image below:

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Very helpful. Thanks! Above somebody said a blue wire, but you're saying tan. But, since I know where it's supposed to plug in, I should be able to track it down now

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[chengny]

Very helpful. Thanks! Above somebody said a blue wire, but you're saying tan. But, since I know where it's supposed to plug in, I should be able to track it down now

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A DK BLU lead was used in later models. It connected to an oil pressure switch, not the sender. The pressure switch was is part of the choke heater circuit. The sender is only to drive the oil pressure gauge.

 

[MisterB]

A DK BLU lead was used in later models. It connected to an oil pressure switch, not the sender. The pressure switch was is part of the choke heater circuit. The sender is only to drive the oil pressure gauge.

I did more digging. Mine has a tan wire in the location on the junction box you indicated. I can't seem to find where it goes though. It's inside of a wire protector with other wires, and goes over behind the back of the engine and I don't see any wires coming out of it.

I think I'll just run a new wire to that spot on the junction box.

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