Gas tank electrical connections

Following... I've just got a new set of gauges for mine and when it gets back from the trimmers I'm going to be looking into the same sort of mysteries!

One is for sensing level, second is for low fuel light and third is ground. There should be a male Spade connector on one of the tiny Bolts that holds the sensor on to the Tank where you can connect the ground wire.

You beat me to it. The real mystery is why it's just hanging there and not grounded to something.bHopefully it just came loose at some point in time.

The 3rd Wire is grounded in the Harness and need to SUPPLY a ground to the Sensor. If this wire is not connected at i.e. one of the tiny Bolts then the Sensor will not work.

I have looked, there is no male spade to plug the third wire into. Maybe it is an after market fuel pick up. The wire must be for the low fuel light. I know it is not working, don't ask me how I know!

The male Spade is the universal type with a tiny Hole in one end and the spade in the other, its slightly bend. It is probably lost but just buy or make a new one. The sensor requires all 3 wires connected to function. Its that simple ;-)

So, hijacking this to continue the same discussion - this is what I have on my gas (petrol over here) tank.

I have a black on the ground / earth, a white black and a yellow black.

The black is ok - as black through this car at least seems to always be ground. Nice.

This leaves the white black and yellow black.

I found a '74 wiring diagram on another thread in here that suggests the white black is the fuel level wire - which is cool, but the diagram shows the low fuel light as being a solid yellow wire not a yellow black.

In my dash the yellow black is consistently connected to the instrument lighting, so being lazy and not belling out the cable is it possible that they could dual purpose the yellow black in the dash to the instruments?

I'll get the multimeter out and answer my own question sometime today - but thought I'd ask here too.

Ah! Notice the pattern of the black stripe on this wire.

It is not straight, it is spiral.

Detomaso did that to distinguish the wires.

This is also found in the fuse panel. You have different "frequencies" of the stripes. This indicates the "polarity" (for lack of a better term) of a wire that is coming into the fuse panel, and one that is going out?

Other than that, pray for divine help on interpreting the wiring harness. They carried abstract creativity to new levels for 1970?

Hey at least the whole car is not all wired in black wire

You are indeed correct Doug! Well spotted.

I'll go looking for a twisty black / yellow instead of a straight yellow / black!

And I know what you mean by all black Joe - my first trade was as an electrician and I've worked on several panels imported from Italy where every wire was black with no wire numbers or diagrams....

It's been a few since then though. Clearly.

Michael, do not confuse the Y/BK 12v(+) for the Instr. Light with the Y coming from the Sensor(-). Your Gauge is supplied with a positive 12v(+) P (Purple) and gets its negative (-) regulated for the level indication by a W/BK and a negative for the low fuel light Y or perhaps in your case a spiraled Y/BK

My Sending unit looks slightly different as it is a combined Sending/Fuel supply..........

diagram:
http://www.panteraplace.com/El...E%20AND%20SENDER.pdf

Found it!!

Hollywood at least helped out a little bit by leaving the globes on the spades when they took the original gauges out.

So, black / yellow twisty is the low fuel light which leaves the white / black as the level

Good roc, My sending unit looks nothing like yours. Mine must be after market. I guess that answers why I don't have the third wire attachment spade.

quote:

Originally posted by goodroc:
Michael, do not confuse the Y/BK 12v(+) for the Instr. Light with the Y coming from the Sensor(-). Your Gauge is supplied with a positive 12v(+) P (Purple) and gets its negative (-) regulated for the level indication by a W/BK and a negative for the low fuel light Y or perhaps in your case a spiraled Y/BK

My Sending unit looks slightly different as it is a combined Sending/Fuel supply..........

Thanks Goodroc - I had figured out the yellow black was the instrument lighting - and also through looking at a gazillion photos and a '74 schematic that the pink in my case (your's is purple) is the "hot" 12V for the instrument supply on the + terminal with the 12 terminal being the lead off to the measuring device be it fuel level or oil pressure.

It's an excellent reminder of my basic DC principles AND instrumentation stuff from back in trade school so I'm kind of actually enjoying it this although it's taking longer than I want it to with work kicking back in for the year...

I am happy the mysteries are solved



and Michael you are right the hot wire is Pink and not purple, also in my case