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

Coolant temperature sensor controls signal voltage to ECM, which applies voltage on circuit No. C10 to 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 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.