DTC 14

DTC 14 - Engine Coolant Temperature (ECT) Sensor Circuit (High Temperature Indicated):

Engine Coolant Temperature (ECT) Sensor Wiring Circuit:

Circuit Description:

The Engine Coolant Temperature (ECT) sensor uses a thermistor to control the signal voltage to the ECM. The ECM applies a voltage on CKT 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 88 to 106°C (190 to 222°F) the voltage will measure about .5 to 1.1 volts.

Test Description: Number(s) below refer to circled number(s) on the diagnostic chart.

1. DTC 14 will set if:
^ Engine running longer than 6 seconds.
^ Signal voltage indicates a coolant temperature above 135°C (275°F).
2. This test will determine if CKT 410 is shorted to ground which will cause the conditions for DTC 14.

Diagnostic Aids:

Check harness routing for a potential short to ground in CKT 410.

Tech I scan tool displays engine temperature in degrees centigrade and degrees fahrenheit. After engine is started, the temperature should rise steadily between 88-106°C (190-222°F) then stabilize when thermostat opens. The cooling fan should turn "ON" at 106°C (222°F).

- Intermittent Malfunctions