'55 Ford car fuel gauge wiring

[Lamar Wadsworth]

Back side of '55 Ford fuel gauge. Car converted to 12V with aftermarket wiring harness. I have the voltage reducer to put on the gauge but need to know which terminal is the power feed and which terminal is for the wire to the sending unit. Need to know to install the reducer on the correct terminal.

Tried to upload photo but not able to. So we'll identify the terminals as left and right looking at the back side of the gauge. Left is closest to speedometer, right closest to outside of vehicle.

 

[dmsfrr]

If you have an original King-Seely gauge and sensor pair look at the first wiring diagram below.

"You do not need to change any switches or gauges. The fuel and temp gauges will work on 6 or 12 V and are not polarity sensitive."
https://www.ctci.org/battery-for-6v-to-12v-conversion/

It's because the old style King-Seely gauge & sensor pairs work on current generated heat with bi-metal switching contacts in the tank sensor. Not variable voltage and heat isn't polarity sensitive. Look closely at the attached diagrams for those heat coil wound parts in the sensor and gauge.
There may be a slight chance you'll need a voltage reducer but you can try without it first.
'Unnecessary parts left out cause no maintenance problems.'

With aftermarket parts follow the instructions in the box.

Just Fyi...
'56 was the first year for 12v negative ground Ford's. While '55 and earlier gauge & sensor pairs aren't particularly voltage or polarity sensitive you might think they're the same as '56 but that isn't correct. Their heating coils and bi-metal switches were very slightly different for full 12v operation, and one-year-only matched to each other.
'57 was the first year that used gauges & sensors with a variable voltage electrical design and added gauge voltage reducer.
.

 

[Lamar Wadsworth]

Thank you!