The coolant temperature sender changes resistance as the coolant temperature increases and decreases.
- Remove the temperature sender from the engine.
- Position the water temperature sending unit in such a way that the metal shaft (opposite end from the electrical connectors) is situated in a pot of water. Make sure that the electrical connector is not submerged and that only the tip of the sending unit's body is in the water.
Heat the pot of water at a medium rate. While the water is warming, continue to measure the resistance of the terminal and the metal body of the sending unit:
- As the water warms up, the resistance exhibited by the ohmmeter goes down in a steady manner: the sending unit is good.
- As the water warms up, the resistance does not change or changes in erratic jumps: the sender is bad, replace it with a new one.
- Install the good or new sending unit into the engine, then connect the negative battery cable.
REMOVAL & INSTALLATION
- Disconnect the negative battery cable.
- Properly drain the engine coolant into a suitable container.
- Disconnect the sender electrical lead and unscrew it. The sender can be found on the engine block or threaded into the thermostat housing/water outlet.
- Install the sensor and tighten until snug.
- Connect the sensor electrical lead.
- Connect the battery cable and fill the engine with the proper type and amount of coolant.