The sending unit is located in a water jacket or coolant passage near the thermostat.
- Check the appropriate fuse before attempting any other diagnostics.
- Make sure the cooling system is full and free of any trapped air.
- Tape a mechanic's thermometer to the radiator return hose (upper hose) securely.
- Disconnect the sending unit electrical harness.
- Using an ohmmeter, check the resistance between the sending unit terminals.
- Resistance should be high (58K ohms) with engine coolant cold 50°F (10°C) and low (2.8K ohms) with engine coolant hot 194°F (90°C).
- If resistance does not drop as engine temperature rises, the sending unit is faulty.