The outside air temperature sensor is a thermistor used in order to control the signal voltage in the electronic climate control (ECC) module. The ECC module control supplies a reference voltage (about 5 volts) on CKT 636 to the sensor. When the outside (ambient) air temperature is cold, the thermistor resistance is high. Therefore, the ECC module will receive a high voltage input. If the outside air temperature is hot, the thermistor resistance is low. The ECC module will receive a low signal voltage input. Refer to Sensor Resistance Table .

When the ignition switch is in the ON position, the ECC module will detect this DTC any time that CKT 636 is at or near zero voltage.

The ECC module will use a default value of -3.3°C (26°F) or 168 A/D counts until the fault is cleared.

This fault will clear as soon as the fault is repaired or when the fault disappears. The system will then return to normal operation. History DTCs may only be cleared by removing and restoring B+ or by using the scan tool.

Visually inspect the sensor connector and harness for corrosion and damage. The resistance value of the sensor must be 300-170,000 ohms. If the resistance is not within the specified value, replace the sensor.

The numbers below refer to the step numbers on the diagnostic table.

2. This step measures the resistance of the outside air temperature sensor.

3. This step inspects for a short to ground in CKT 636 (DK GRN/WHT).

4. This step inspects for intermittents and tests for a malfunctioning ECC module

5. This step repairs the short to ground in CKT 636 (DK GRN/WHT).

6. This step replaces a defective outside air temperature sensor.

7. This step replaces a defective ECC module.