DTC 14

Code 14 Chart:

Wiring Diagram For CTS:

CIRCUIT DESCRIPTION:

The Coolant Temperature Sensor (CTS) uses a thermistor to control the signal voltage to the ECM. The ECM applies a voltage on circuit 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 85 to 95°C (185 to 203°F) the voltage will measure about 1.5 to 2.0 volts.


TEST DESCRIPTION: The numbers below refer to circled numbers on the diagnostic chart.

1. A Code 14 will set if:
a. Signal voltage indicates a coolant temperature above 135°C (275°F) for two seconds.

2. This test will determine if circuit 410 is shorted to ground which will cause the conditions for a Code 14.


DIAGNOSTIC AIDS:

1. Check harness routing for a potential short to ground in circuit 410.
2. A "Scan" tool displays engine temperature in degrees centigrade. After the engine is started, the temperature should rise steadily between 88-106°C (190-222°F) then stabilize when thermostat opens.
3. If an intermittent Code 14 exist, see DIAGNOSIS BY SYMPTOM.