DTC 14

Code Chart 14:

ECT 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 (85°C to 95°C) the voltage will measure about 1.5 to 2.0 volts.

TEST DESCRIPTION: Number(s) below refer to circled number(s) on the diagnostic chart.

1. DTC 14 will set if:

^ Signal voltage indicates engine coolant temperature above 135°C (275°F) for 1 second.

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. A Tech 1 scan tool displays engine temperature in degrees centigrade. After engine is started, the temperature should rise steadily to about 90°C then stabilize when thermostat opens. - Intermittent Malfunctions