When coolant temperature is low, the resistance of the sending unit is high, restricting the flow of current through the gauge and moving the pointer only a short distance. As coolant temperature rises, the resistance of the sending unit decreases, causing a proportional increase in current flow through the sending unit and corresponding movement of the gauge pointer.
The sending unit may only be tested for operation. There is no calibration, adjustment or maintenance required.
See Figures 1, 2, 3 and 4
- Remove the sensor from the vehicle.
- Immerse the tip of the sensor in container of water.
- Connect a digital ohmmeter to the two terminals of the sensor.
- Using a calibrated thermometer, compare the resistance of the sensor to the temperature of the water. Refer to the engine coolant sensor temperature vs. resistance illustration.
- Repeat the test at two other temperature points, heating or cooling the water as necessary.
- If the sensor does not meet specification, it must be replaced.
REMOVAL & INSTALLATION
For the location of your unit, see the accompanying illustrations.
- Disconnect the negative battery cable.
- Drain the cooling system into a suitable container.
- Disengage the electrical connector at the temperature sender/switch.
- Remove the temperature sender/switch.
- Apply pipe sealant or Teflon® tape to the threads of the new sender/switch.
- Install the temperature sender/switch and connect the electrical connector.
- Connect the negative battery cable. Fill the cooling system.
- Run the engine and check for leaks.