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...Which might be kind of neat to try doing. If you could find a gauge with a resistance-based sending unit, you could install it in place of the stock unit and re-write the ECU's conversion table to make it's input valid. I'm not totally clear on how the ECU reads the sensor. The stock sensor is a thermistor, which changes resistance based on the temperature. It appears the ECU supplies 5v to the sensor and the voltage drop (not the return voltage itself) is used to determine the temperature. The sensor creates a lot of resistance when cold, and less resistance when warm. However, the ECU's table shows a higher voltage equating to a cold temperature, and a lower voltage equating to a higher temperature. I'm no electrical engineer, but this seems backwards to me because I would think that higher resistance would result in a lower return voltage and less resistance would result in a higher return voltage. My guess here is that the ECU reads the difference in voltage--how much the voltage drops. So if the ECU supplies 5v and it only drops .96v, the temperature would indicate 99C (about 210F). That or I'm completely misunderstanding the relationship between resistance and voltage.
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