Code 14 - Cts Circuit (High Temperature Indicated): Notes

Coolant temperature sensor controls signal voltage to the ECM. The ECM applies voltage on circuit No. C10 to the sensor. When engine is cold, thermistor resistance is high and ECM will see a high signal voltage. As engine warms, sensor resistance decreases and ECM will see a low signal voltage. When engine reaches normal operating temperature, signal voltage will be approximately 1.5-2.0 volts at the ECM.

1. Code 14 will set if signal voltage indicates a coolant temperature greater than 275°F (135°C) for 6 seconds.
2. This determines if circuit No. C10 is shorted to ground, which will cause the conditions for Code 14.