Code 14 - Coolant Sensor Circuit Shorted: Notes
The Coolant Temperature Sensor uses a thermistor to control the signal voltage to the ECM. The ECM applies a voltage on circuit No. 410 to the sensor. When the engine is cold, sensor resistance is high and the ECM sees a high signal voltage. As the engine warms, the sensor resistance becomes less and the voltage drops. At operating temperature, voltage will measure about 1.5-2.0 volts at ECM terminal "YC16".
Coolant temperature is used to control, fuel delivery, Engine Spark Timing (EST), Canister Purge (CCP), cooling fan, Idle Air Control (IAC), and Torque Converter Clutch (TCC).
COOLANT TEMPERATURE SENSOR RESISTANCE VALUES
| Temperature In °F (°C) | Ohms Resistance Should Be: |
|---|---|
| 210 (100) | 185 |
| 160 (70) | 450 |
| 100 (38) | 1800 |
| 70 (20) | 3400 |
| 40 (4) | 7500 |
| 20 (-7) | 13,500 |
| 0 (-18) | 25,000 |
| -40 (-40) | 100,700 |
NOTE:
Test numbers refer to test numbers on diagnostic chart.
- Code 14 will be set if signal voltage indicates temperature greater than 285°F (140°C) and engine has been operating for more than 128 seconds.
- This test will indicate if circuit No. 410 is shorted to ground and set a code 14.