Code 14 - Coolant Sensor Signal Volt Lo (A/F/J/N/P Body)
The Coolant Temperature Sensor uses a thermistor to control 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 a high signal voltage. As the engine warms, the sensor resistance becomes less. The voltage signal will be about 1-1.5 volts at terminal 4 of ECM. Code 14 will set if signal voltage indicates a coolant temperature above 275°F (135°C) for more than 4 seconds. Coolant temperature is one (1) of the inputs used to control fuel delivery, engine timing (EST), idle (IAC), and converter clutch (TCC).
- If voltage is above 4 volts, the ECM and wiring are okay. If checking resistance at coolant sensor is difficult because of sensor location, disconnect Black ECM connector and check resistance between terminals 4 and 11.