1970 combo gauge wiring Options

[Cfletch]

Looking for some specific help here regarding a 1970 Combo gauge and wiring.

Basically I need to install my new combo gauge that has 3 separate gauges in for fuel, oil temp and oil pressure. I had John Bell make this gauge for me. I can't find a good wiring diagram that will show me colors of wires and where they belong on the back of even a normal combo gauge for that era and I am a little stuck.

Gauge has the above, but also the original normal stuff such as brake, alternator, oil pressure light and all of that. Can someone point me ideally a color coded wiring diagram specifically for the gauges so I can connect up the normal stock stuff and then worry about the new stuff such as oil temp and pressure?

[JeffBowlsby]

Find the factory schematics here: https://bowlsby.net/914/WiringHarnesses/

For 1970 the drawing is only in B/W.

You might review the 1971 which is in color, and may be close, but you’ll need to verify as you go.

[Cfletch]

Find the factory schematics here: https://bowlsby.net/914/WiringHarnesses/

For 1970 the drawing is only in B/W.

You might review the 1971 which is in color, and may be close, but you’ll need to verify as you go.

Checking the diagram for 1970, I might be blind, but I am not seeing color references of the wires

[JeffBowlsby]

Uh huh…I said that. Look at the 1971 schematic.

[Cfletch]

Uh huh…I said that. Look at the 1971 schematic.

Gotcha, I mistook what you meant by b/w as its just not colored, but wires would be labeled, my mistake.

[JeffBowlsby]

Simple misunderstanding, no worries. Hope you figure it out.

[nditiz1]

I just did this yesterday so feel free to reach out directly.

Green/Red - factory idiot light for oil pressure (already run to gauge)
Green/Black - Oil temp (should exist on passenger side harness near battery tray, will terminate before shifter unless you have the appearance package and it goes to center console)

Those are the factory 914 colors which should already exist in your car. You will want to add/run an additional wire for the oil pressure number gauge as the factory harness never included one.

[Dave_Darling]

Use the regular wiring for the warning lights and the fuel gauge.

You will have to run wires for the oil temp and oil pressure, in addition to having senders for those. (The 911 engine should have them already; a 1970 1.7 will only have a sender for the oil pressure light which will not run a gauge correctly.)

Generally, the gauges will need switched power and possibly a separate ground, though often the sender itself provides the ground for the gauge. Additionally, there will often lights for illuminating the gauge itself.

Look on the connector on the gauge module for numbers and symbols. There will likely be something like "30" for switched power, and "G" for the sender, and a set of three parallel lines for the ground. Illumination lights will just have a socket.

For power, use a piggyback electrical connector (double check the sizes; that is just an example!) from the power connection of the one gauge module and daisy chain to the other two. You can similarly extend the illumination light power supply and ground if need be.

--DD

[IronHillRestorations]

Hey Colin. @Cfletch
Review the information I sent with your engine harness.

The 914 only has a circuit for oil pressure warning light and oil temp. The oil temp wire is green with black stripe. It’s in the bundle for the console gauges. You’ll need to extend it from the console area to the gauge.

You’ll use the green wire with white stripe at the heater lever and extend it with the solid green wire to the gauge.

All gauges require power, ground, and sensor wires, in addition to the gauge illumination wires.