Fix for an over-reading temp gauge

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halfpenny
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Fix for an over-reading temp gauge

Post by halfpenny » Mon Dec 12, 2016 5:06 pm

My temp gauge read 105 in normal running - annoying when I was fairly sure the engine was not overheating, and not much time to spot rising temp in traffic. Stabilized voltage supply checked out fine. Then my fuel gauge occasionally dropped to zero. Diagnosed as a bad earth from the sender. Fixed that, and now the temp gauge reads 90.
I understand the problem and solution, but would not have thought to check the sender earth without a prompt. Worth checking if you have a similar problem, since they are on the same electrical circuit.



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scimjim
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Re: Fix for an over-reading temp gauge

Post by scimjim » Mon Dec 12, 2016 7:12 pm

I don't understand the solution - the fuel sender earth is totally unrelated to the engine temp circuit?


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Re: Fix for an over-reading temp gauge

Post by Pepe » Mon Dec 12, 2016 8:28 pm

I assume he means the same GND connection? This is "daisy chained" from one earth behind the meters... at least in mine...


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Re: Fix for an over-reading temp gauge

Post by scimjim » Mon Dec 12, 2016 8:30 pm

That's the earth for the back light.


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Re: Fix for an over-reading temp gauge

Post by halfpenny » Mon Dec 12, 2016 9:46 pm

I wouldn't say the fuel gauge and temp gauge circuits are totally unrelated - they are the only two circuits fed from the voltage stabiliser output. In any event I am just reporting a phenomenon which may help others with a similar problem.



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Re: Fix for an over-reading temp gauge

Post by scimjim » Mon Dec 12, 2016 10:05 pm

The earth circuits are unrelated (well apart from the battery :-))


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SECURE DRY STORAGE FOR YOUR SCIMITAR

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Re: Fix for an over-reading temp gauge

Post by toomanysabres » Mon Dec 12, 2016 10:14 pm

The voltage regulator has to be earthed otherwise the bi-metal oscillating switch won't work. It will probably pass through 12volts and give a high reading. Although the fuel gauge would respond similarly.


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