Gauge wiring

[Dothang67]

I just finished wiring the mustang, everything went very smooth, and what I thought to be the most straightforward wiring is giving me some headaches.

I can't get the gasoline and temperature gauges to make a reading from the sensors. Both sensors were working a few weeks back when I started this project, and both have the boot-style connector (only on the sensor side).

The wiring is as follows:

Sensor ------> Gauge ______> Earth

What am I missing?


EDIT: I just found a diagram explaining that I missed a connection, that should explain a couple of doubts I had.

 

[2+2GT]

The wiring is as follows:

Sensor ------> Gauge ______> Earth

What am I missing?

This:

12v+ -------- CVR 7v+ ------- Gauge ------- Sensor -------- Earth.

 

[Dothang67]

Yeah, and I thought current might flow magicly through my gauges

I rewire the gauges and still doesnt work, but I just checked with a voltmeter and seems that the CVR isn't feeding the 7 volts to the gauges, so I guess its time to change that one piece.

Thanks 2+2GT

 

[Dothang67]

The disadvantages of not living in the US.. I couldn't find a Ford CVR, just a Dodge one, and doesn't seem to work correctly. Could I fab a workaround to this issue? Like using a circuit board with some resistances to drop the voltage from the 12V source to the 6V the gauges need?

 

[tx65coupe]

I would recommend using and electronic ICVR. I think NPD and maybe Paddock sells them. Those reproduction ones are kinda junky. You can also make your own for not much money. Here is a write up on it. I did basically the same thing on mine. IVR

 

[Dothang67]

Thanks pal, i just did it and works like a charm, steady 5-volt output. The water temp is working good now, but the fuel one doesn't, it pegs the needle.

My question now is, how does the fuel sending unit grounds? I saw an old picture in another forum which shows a grounding cable coming from the fuel sending unit, does this applies to Fords also?

 

[zigmont]

Fuel guage

12v > CVR > Fuel guage > Fuel sending unit which is grounded to the tank through the locking ring that secures the sending unit to the fuel tank, which is in turn, is grounded to the body of the car.
The fuel sending unit contains a variable resistor that is attached to the float arm. It (the resistor) controls the amount of ground the guage gets. The more fuel in the tank, the higher the float arm, the less resistance to ground, and the higher the needle reads.
If you ground the guage directly, it will peg the needle. It (the guage) has to go through the fuel sending unit which will provide the amount of ground the guage needs to correctly show the fuel level.
Hope this helps.