Quote:
Originally Posted by Gene F
DMSFRR, doesn't going form 6 to 12 make the gages go babanas? What about the fuel tank gage?
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Not usually, if they were working well before. Here's a quote from the link I included in reply # 2 above...
"The fuel and temp gauges will work on 6 or 12 V and are not polarity sensitive."
The old style King-Seeley gauges & sensors do not use variable resistance for gauge needle movement. That started in '57 when Ford upgraded them, and many other parts as well.
Pre '57 gauge circuits use current flow and heat sensitive bi-metal switching contacts. The bi-metal contacts in the sensor may cycle at a different rate on 12v but the result at the gauge is effectively the same. In some cases a voltage reducer may be helpful for pre '57 gauge circuits.
Example '55 and '57 diagrams below.
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