Need resistance wire to repair vintage Ford electric gauges

Probable causes:

1. Wire from dash gauge to sending unit is broken or the connection is corroded hindering electrical connection.
   
2. Resistance wire inside sending unit is broken
   
3. Lack of proper grounding between sending unit and tank or between tank and chassis

Narrow the cause by testing. At the bottom on the following webpage you will find testing procedures as well as repair. (It is always helpful to mention brand and model and year).
Fuel Gauge Testing

Fiats have a reputation for electrical/electronic problems as they age and even when they are not very old they can manage strange things that even sometimes defeat the dealers, though the same can be said of many modern vehicles. I used to look after a Ducato motorhome and fortunately didn't need to get involved with much electrical work - the only faults were caused by the coachbuilders rushing around and being careless and not by Fiat.

I am not sure if the temp gauge is driven by the engine management or is a traditional circuit but either way the temperature gauge is in effect a voltmeter of sorts. Assuming the gauge is ok, the reading will only fluctuate if the voltage in the circuit fluctuates and that could mean the supply voltage is fluctuating or the resistance of the ground path is fluctuating.

With the traditional circuit the gauge is supplied by an electronically stabilised voltage and the ground path resistance is varied by the engine coolant temperature sensor and fluctuations could be anything from a faulty instrument voltage regulator, through faulty wiring or connections to the temperature actually fluctuating.

If the gauge is driven by the engine management the same approximately applies but checking the circuit becomes much more complex due to the need for circuit diagrams and specialised test equipment, though these would not be needed just to check the security of the gauge in the printed circuit of the instrument panel.

Either the gauge itself, or the wire from gauge to tank, or the sending unit in the tank. Most of the time it is a problem with the sending unit.

They work like this: in the instrument cluster, a small voltage regulator sends low voltage through the gauge, into the wire to tank, and to the sending unit. The unit has a variable resistor that varies according to the fuel level, measured by the float arm attached to the unit. What it (the gauge) actually measures is resistance to ground-the current goes to a ground point after going through the variable resistor in the sending unit.

You can check if problem is the gauge or the sending unit by grounding the fuel gauge wire at the gas tank connector. Pull the electrical connector apart and locate the fuel gauge wire. Jumper that wire to ground on the frame while watching the fuel gauge needle for movement. DO NOT ground it for more than a split second, just touch to ground while someone watches the gauge. If the gauge needle moves at all (will probably go to full or empty), then the problem is the sending unit in the tank. The gauge is good, so is the wire from gauge to tank. I should mention that doing this test can possibly blow the meter (gauges) fuse in the fuse panel- why I said to do it just for a brief moment.

usually grounded wire--to in tank fuel meter--coolant temp sending unit--or voltage regulator (alternator).--Check prior repairs for hint .What has been removed and or replaced recently??? Fuel pump or tank? Intake Manifold? Alternator? start looking for pinched wire and or shorted component there.

If you have replaced the sensor, check the wires at the back of the plug. Pull them one at a time, if they stretch it is a broken wire. When you get a high reading code. It is either it's unplugged or a wire is broken.

1= this happen because th IVR fail, see the diagram and test it use the DVOM OR VOM for test the IC .l
2= test the thermistor or sensor for defective.
3= if the voltage of IVR is out of regulation in this case +12vdc,test for ground.if is o.k test by the side of battery side of the IVR, if this voltage is present replace the IVR, if regulated voltage is withing specifications, test the printed circuite from the IVR to the gaues, and if there are open circuite replace the circuit board. OF course test the fuse too.
God bless you

Ford 150 Van No Start No Crank Same problem aftermarket remote start problem !
Watch the second part too . Do you know what a wiring diagram is ? Look under dash or the hood an see where the remote start is hooked up , what wires ! You can find a wiring diagram here at http://www.bbbind.com/free_tsb.html Enter the vehicle info. year , make , model an engine size . Under system click on engine , then under subsystem click on starting . Click the search button , then on blue link . You'll see all the componets in the starter circuit .

SOUND LIKE FUEL LEVEL SENDING UNIT FAULTY.

Your sending unit is bad.

Here is the circuit:

(+)———»IS———»VR———»G———»SU———»(Gnd)

IS: Ignition Switch
VR: Gauge Voltage Regulator (mounted with the gauges)
G: Gauge
SU: Gas tank sending unit

The gauge deflects through heating a strip of metal that bends when hot. There is resistance wire wrapped around that strip to heat it up. One end of that wrap of wire is attached to the gauge "voltage regulator, the other end to the tank sending unit. The "voltage regulator" cycles between conducting power from the Ign. Sw. to the gauge, and disconnecting the gauge from that voltage. The sending unit in the tank varies resistance in response to the position of the float in the tank. Full: virtually no resistance. Empty: a lot of resistance. When the tank is full, during the period the "voltage regulator" is on, the strip of metal heats up a lot, because the sender has almost no resistance. When the tank is empty, during the period of time the "voltage regulator" provides voltage, the strip barely gets heated, deflecting the gauge hardly at all, because the resistance the sending unit creates limits the current through the gauge.

You have almost no continuity through the sending unit except near full, and at a few other position. Replace the sender, and you will have a functioning gauge.

Voltage from the battery goes through the ignition switch, through a device in the instrument cluster called a voltage regulator (though it is really misnamed), through the gauge, through the wiring to the gas tank, through the sending unit in the gas tank to ground.

The sending unit is an electrical wiper that slides across a peice of resistance wire. the movement of the float moves the wiper. If the sending unit no longer makes electrical continuity, the gauge will read zero. If the sending unit wiper is shorted out, the gauge will read full.

Try grounding the wire at the tank to see if the gauge maxes out, then disconnect it to see if the gauge zeros out. If all that happens, your problem is the sending unit in the tank. If none of that happens, your problem lies closer to the front of the car. While you are under there, you should measure the resistance from the terminal on the tank to ground, just to verify that the sending unit makes some electrical contact.

If the other gauges work OK (temp, oil pressure) then the "voltage regulator" is probably working fine, and the problem is the gauge itself.

If you have no other gauges (excluding speedometer, tachometer and battery voltage meter -- they work differently), then try this:

Put a voltmeter on the part of the fuel level gauge that is supplied by the "voltage regulator." The voltage there should regularly cycle between near zero to 10 or 12, back to near zero, etc. If you get that cycling, then it is most likely the gauge.