Code 14 - Coolant Sensor (Temperature Too High): Notes

The coolant temperature sensor uses a thermistor to control the signal voltage to the ECM. The ECM applies voltage on circuit No. 410 to the sensor. When the engine is cold the sensor (thermistor) resistance is high, therefore the ECM will see high signal voltage.

As the engine warms, the sensor resistance becomes less, and the voltage drops. At normal engine operating temperature the voltage will measure about 1.5-2.0 volts.

NOTE: Test numbers refer to test numbers on diagnostic chart.

NOTE: The "SCAN" tester displays engine temperature in degrees centigrade.

Code 14 will set if, signal voltage indicates a coolant temperature above 275°F (135°C) for 2 seconds.
This test will determine if circuit No. 410 is shorted to ground which will cause the conditions for Code 14.