Duster temp gauge problems

My two cents for several test methods:

• With the engine warmed up and ignition ON, fasten a wire at one end to battery ground and the other to the sensor body. This will verify a ground issue.
• With engine at normal operating temperature, ignition OFF, sensor wire removed, measure the resistance of the sensor from its terminal to the sensor body. Should be approximately 30 ohms, give or take some. If 100 – 150 ohms, it’s the wrong sensor. If no continuity, bad sensor.
• Engine OFF, sensor removed, sensor wire connected, connect a ground wire as above, ignition ON, use a heat gun (or wife’s hair dryer) to heat the end. Should see the gauge move. Or, measure the resistance as above procedure. This verifies the whole circuit, minus a good ground.
• Use a resistor of approximately 30 ohms, sensor wire removed and connected to resistor, the other end to battery ground, ignition ON, gauge should read around half scale.
• Sensor removed, read the resistance of the cold sensor and when heated. Reference post #6 for correct range.

From your info already noted, it points to the wrong sensor or a faulty one.