DTC 14

Chart - Code 14 Coolant Sensor Circuit (Signal Voltage Low):

Wiring Diagram for Coolant Sensor Circuit.:

CODE 14 - COOLANT TEMPERATURE SENSOR (HIGH TEMPERATURE INDICATED)


Circuit Description:


The coolant temperature sensor uses a thermistor to control the signal voltage to the Electronic Control Module (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 degrees C to 95 degrees C) the voltage will measure about 1.5 to 2.0 volts.


Test Description: Numbers below refer to circled numbers on the diagnostic chart.
1. Code 14 will set if:

-Signal voltage indicates a coolant temperature above 135 degrees C (275 degrees F) for 3 seconds.
-Engine running longer than 2O seconds.

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


Diagnostic Aids:

Check harness routing for a potential short to ground in CKT 410. "Scan" tool displays engine temp. in degrees centigrade. After engine is started, the temperature should rise steadily to about 90 degrees C then stabilize when thermostat opens. Refer to "DIAGNOSIS BY SYMPTOMS - NO TROUBLE CODE STORED".