DTC 14

Code 14 Chart:

Code 14 Wiring Diagram:

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.

NOTE: Because of all the possible color code combinations used on electrical wiring diagrams, always refer to SCHEMATIC DIAGRAMS/ELECTRICAL AND ELECTRONIC WIRING DIAGRAMS/ECM CONNECTOR IDENTIFICATION for correct color code identification of circuit.


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 130~C (266~C) 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 (194~F), then stabilize when thermostat opens. See TESTING PROCEDURES/DIAGNOSIS BY SYMPTOM/INTERMITTENTS.

Check For:


- Poor Connection or Damaged Harness. Inspect ECM harness connectors for backed out terminal GE16 or BB6, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection, rubbed through wire insulation or a wire broken inside the insulation.

- 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.