Fuel and temperature gauges — checking (Mazda Capella GC)

1. If the fuel level or temperature gauges are not giving accurate readings, the problem may be in the gauge or sensor. Using simple equipment (multimeter and a set of resistors) you can check the meters and sensors.

Fuel level indicator

2. Access the fuel level sensor by removing the rear seat and inspection cover. Disconnect the electrical wiring connector.

3. Connect a resistor of known value from 8 to 96 ohms between the "Y" connector and ground (car metal). Make sure no other wires are shorted to ground, then turn the ignition on.

4. Allow the meter to stabilize for two minutes, then compare the expected measurement with the actual measurement.

5. Repeat the test, if possible, with other resistor values within the stated range. Before replacing resistors, turn off the ignition.

6. If the meter shows "full" or "empty" regardless of the resistor value, the wiring to the meter may be short-circuited or damaged, respectively. In other words, inaccurate data due to damage in the meter.

Checking the fuel gauge

Fuel level indicator readings at different resistances

Fuel level indicator sensor

7. Remove the mounting screws and take out the sensor.

Warning: Take appropriate precautions against spontaneous combustion and vapor intoxication. Remove the sensor from the vehicle.

8. Connect the multimeter, set the resistance to be measured to the sensor terminals. Move the float up and down, compare the resistance in different positions with the values.





9. If the resistance does not change as defined, the sensor must be replaced. Finally, install the sensor.

Temperature indicator

10. Disconnect the electrical connector from the temperature gauge sensor (located behind the thermostat housing).

11. Connect a resistor of known value and within the range shown in the figure between the sensor connector and ground.

12. Make sure the wires are not shorted to ground, then turn on the ignition. Allow the meter to stabilize for two minutes, then compare the expected reading to the actual reading. Repeat with other resistors if possible.



13. If the meter shows maximum or minimum, regardless of the resistor value, then the wiring is short-circuited or damaged.

Analog temperature gauge data for different resistances - models with tachometer

Analog temperature gauge data for various resistances - models without tachometer

Temperature indicator sensor

14. Drain the fluid from the cooling system below the sensor level. Unscrew the sensor and remove it.

15. Hold the sensor on the water tray so that the light bulb is submerged. Connect the multimeter, set to resistance measurement, to the housing and clamp of the block. Heat the water to 80°C: the resistance at this temperature should be 53.5±4.2 Ohm.



16. If the resistance is outside the limits, replace the sensor.

17. Install the sensor and fill the cooling system.