Coolant Temperature Sensor (CTS)

The CTS is located in coolant passage. The ECM sends a 5 volt signal to the CTS. This 5 volt signal is reduced by the resistance of the CTS and a voltage signal goes back to the ECM. When coolant temperatures are low, CTS resistance is high and a low voltage signal is sent to the ECM. When coolant temperatures are high, CTS resistance is low and a higher voltage signal is sent to the ECM. Coolant sensor problems may set a Code "14" or "15".