DTC 14

Code 14 Chart:

Code 14 Wiring Diagram:

CIRCUIT DESCRIPTION:


The coolant temperature sensor uses a thermistor to control the signal voltage at 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 ECM terminal "GE16" voltage will be high.

As the engine warms, the sensor resistance becomes less, and the voltage drops. At normal engine operating temperature, the voltage will measure about 1.5 to 2.0 volts.

Code 14 will set if:

^ Signal voltage indicates a coolant temperature above 147~C (296~F) for 0.4 seconds.

^ Engine running longer than 10 seconds.


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

1. This will determine if the coolant sensor is indicating a high temperature to the ECM.

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

If code 14 is set, the ECM will use a default coolant sensor value of 49~C (120~F) for fuel control. The scan tool will read actual values, not default values.


DIAGNOSTIC AIDS:


^ Intermittent Test: If connections and harness check OK, "Scan" coolant temperature while moving related connectors and wiring harness. If the failure is induced, the "coolant temperature" display will change. This may help to isolate the location of the malfunction.

^ Shifted Sensor: The "Temperature To Resistance Value" scale may be used to test the coolant sensor at various temperature levels to evaluate the possibility of a "shifted" (mis-scaled) sensor, which may result in driveability complaints.

^ Poor connections or rubbed through wire installation.