DTC 14

Code 14 - Coolant Temp. Sensor Circuit (High Temp. Indicated):

Wiring Diagram for Coolant Temp. Sensor Circuit:

CODE 14 - COOLANT TEMPERATURE SENSOR CIRCUIT (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~C to 95~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~C (275~F) for 3 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 temperature in degrees centigrade. After engine is started, the temperature should rise steadily to about 90~C then stabilize when thermostat opens. Refer to "Intermittents" in Diagnosis By Symptoms - No Trouble Codes Stored.