MotoMeter Temperature ohm range?

[KMW]

Hi, does anybody know what ohm range the temperature sensor should be for a MotoMeter gauge?
I have a 40mm MotoMeter temp gauge that I would like to get working.
Gauge is in working order but using a VDO dipstick it maxes out, looks like the MotoMeter needs much higher resistance than the current VDO gauges.

/Anders

[tstracy39]

Motometer used a wide assortment of ohm ranges for their gauges, even among gauges produced in the same batch. I can confirm this because I've taken apart otherwise identical NOS MM gauges from the same source and found resistors with different ohmages in each. Unless you have the sender that originally came with the gauge, you are SOL.
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[Zwitterkafer]

If all you have is the temp gauge, you can still figure out the resistance range needed for the sender. To do this, you need the car battery (or equivalent DC voltage source) and a decade resistor box. The decade resistor box is a network of precision resistors (usu 1%) and switches that allows you to insert series resistances into your gauge circuit. Once you are in the ballpark area that moves the gauge to about midscale, (start with high resistances to avoid pinning the gauge) then adjust those resistances up and down and make a graph of gauge temperature readings vs. series resistance values. The graph should be pretty close to a straight line. The slope of the line will tell you the ohm / deg C response of the needed sender, as well as the required high and low limit resistance values. If a decade resistor box is not available, this test could also be done with a linear potentiometer of suitable range, or <shudder> discrete resistors.....but the actual resistance values have to be confirmed with an ohm-meter.
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"Criticism comes easier than Craftsmanship"
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[tstracy39]

The temp senders (I'm pretty sure) are only thermistors, so you could somehow jury-rig a thermistor in place of the sender (maybe encase it in epoxy, and mold in some male threads?) if no gauge manufacturers make one to that particular spec.
_________________
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