Fuel gauge not working when mounted to the dash

[Hueyjockey]

I’m having issues with the fuel gauge in my 1965 Dodge Dart GT. When the instrument cluster is unscrews and off the body, the fuel gauge works fine. Once the instrument cluster is mounted to the dash, the gauge does not work. I think I have some stray voltage because when the cluster is off the dash, the blinker light has a slight glow. But, the fuel gauge reads correctly. Once the cluster is mounted to the dash, the blinker light glow is gone, but the fuel gauge doesn’t work. All the other gauges work fine. Has anyone had this issue? Any recommendations on what to troubleshoot?
Thnx, Jay

 

[Dana67Dart]

Most clusters MUST be grounded for all the lights and gauges to work properly.

Infact you can burn out your gauges with out the ground. The IVR MUST be grounded to function and without that ground it provides a full 12v to the gauges.

The lamp lighting suggests it is completing a cir somewhere

That your gauge works when un grounded is most likely a fluke.

Might be a bad connection when the wires are under tension

 

[RustyRatRod]

The cluster grounds through the screws that hold it in place, as mentioned. That's a kinda poor ground. I always run a separate ground wire from the cluster to the dash frame. It sounds like a bad ground.

 

[67Dart273]

I cannot imagine what would be the cause. Doesn't that cluster have the IVR internal to the fuel gauge? Even if not, the IVR feeds all gauges except the ammeter. I wonder if the sender wire is being pinched, or maybe the connector to the PC board is being stressed such that the sender wire becomes "open." I would start by checking tightness of the harness connector to pc board connections AND THE pins on the pc board (If they are at all loose, clean, flux, and solder them) Make sure connector fits tight. Run a pigtail ground to the cluster as suggested, and with it out of the dash, does it work? If so, it is not a grounding problem

"General path."

Key switch 12V makes it's way to the IVR, which must also be grounded. The output goes to all gauges except ammeter, AKA temp, fuel, and oil if equipped. (Loosen/ retighten the gauge stud nuts on all gauges a couple times to "scrub" the connections clean.

Through each gauge, and out the sender terminal, each sender lead makes it's way on the PC board to the connector, where wiring leads back to each sender to ground. All gauges (except ammeter) work the same way, and use the same resistance senders.

IF THE IVR is internal to the gauge in this car, it is illogical that the fuel gauge would not work. If so, the problem must be in the sender or sender wiring, OR THE ACUTAL FUEL gauge has a problem

 

[Hueyjockey]

I cannot imagine what would be the cause. Doesn't that cluster have the IVR internal to the fuel gauge? Even if not, the IVR feeds all gauges except the ammeter. I wonder if the sender wire is being pinched, or maybe the connector to the PC board is being stressed such that the sender wire becomes "open." I would start by checking tightness of the harness connector to pc board connections AND THE pins on the pc board (If they are at all loose, clean, flux, and solder them) Make sure connector fits tight. Run a pigtail ground to the cluster as suggested, and with it out of the dash, does it work? If so, it is not a grounding problem

"General path."

Key switch 12V makes it's way to the IVR, which must also be grounded. The output goes to all gauges except ammeter, AKA temp, fuel, and oil if equipped. (Loosen/ retighten the gauge stud nuts on all gauges a couple times to "scrub" the connections clean.

Through each gauge, and out the sender terminal, each sender lead makes it's way on the PC board to the connector, where wiring leads back to each sender to ground. All gauges (except ammeter) work the same way, and use the same resistance senders.

IF THE IVR is internal to the gauge in this car, it is illogical that the fuel gauge would not work. If so, the problem must be in the sender or sender wiring, OR THE ACUTAL FUEL gauge has a problem

Good info, thanks