This page will help you modify your 1994-1997 Miata temperature gauge. If your gauge doesn't look like the one pictured here, you have a different year.. try the 90-93 page (Here) or the 94-97 page (Here). To Date, I have not modified a 99-03 gauge, so this info has been collected from others that have done the modification themselves.
Wallyman
| I used 10 ohms and 180 ohms. You add the 10 ohm resistor in series with the sender, then you place the 180 ohm resistor between ground and the 10 ohm resistor (the end away from the sender) Before resistors but with diode shorted out: 
After adding the resistors. Note the diode is still shorted out. Note also that the 2 new resistors, the left-hand factory resistor, and the diode (still shorted out), are all connected together.  End result: At skinny line on left, 85C. 1/4th: 92C 40%: 97C 1/2: 99C 3/4th: 110C At skinny line near 'H': 115C Now, what I want is a simple mod for my M2 that just plugs in between the sensor and the sensor wire. Simplify, simplfy! Jim in Tucson |
REFERENCE: Here is a plot of the Thermistor (temperature sender in the engine) with Temp vs. resistance.
REFERENCE: Here is a visual comparison of temperatures shown on the stock and my modified gauge.
