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Re: Yanmar Oil Pressure Pegged
Electrical oil pressure sending units typically work by changing the resistance in proportion to the oil pressure. As the oil pressure rises the resistance, in OHMs, goes up. This change in resistance may not be linear. The path of current is likely from the negative terminal of the battery and negative bus through a ground wire to the engine block. Then through the oil pressure sending unit where the resistance is varied with the change in oil pressure. Continuing out a single wire to the oil pressure gauge and finally out through another wire to the positive bus and to the positive side of the battery. Any poor connections along this route will add resistance to the circuit and show up as a higher then normal reading. This, of course is simplified and your system may be different. Don't be surprised if you remove the sending unit to check the pressure and it is ok, then reinstall the sending unit only to find the problem went away.
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