DTC 01

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION

The outside air temperature sensor is a thermistor used to control the signal voltage at the H-A/C control. The H-A/C control supplies a reference voltage (about 5 volts) on CKT 735 to the sensor. When the outside (ambient) air temperature is cold, the thermistor resistance is high: therefore, the H-A/C control will receive a high signal voltage input. If the outside (ambient) air temperature is hot, the thermistor resistance is low; therefore, the H-A/C control will receive a low signal voltage input. A DTC 01 will he set if the resistance is low; therefore, the H-A/C control will receive a low signal voltage input. A DTC 01 will be set if the resistance seen between CKT 735 and CKT 1791 is above 100.7 k ohms.

DTC WILL SET WHEN

With ignition in "RUN," the H-A/C control will detect this fault anytime that CKT 735 stays at 4.5 volts or higher.

ACTION TAKEN:

DTC 01 will set in the H-A/C control. The ACAC system will use a default value of 49°F until the fault is cleared. This can be seen by displaying pointer -31 for the outside air temperature sensor.

DTC WILL CLEAR WHEN

This fault will clear as soon as the fault has been repaired. The system will return to normal operation.


DTC CHART TEST DESCRIPTION

Number(s) below refer to circled number(s) on the diagnostic chart.

1. This test checks for HVAC DTC(s) and should clear any intermittent DTC(s).

2. This test checks resistance of outside air temperature sensor.

3. This test checks for normal to above voltage on CKT 735.

4. This test checks for an open in CKT 1791.

DIAGNOSTIC AIDS

Visually inspect sensor connector and harness for damage, corrosion or water intrusion. The resistance value of the sensor must be between 282 ohms and 100.7 k ohms [underhood temperature below 82°C (180°F) and above -34°C (-30°F)]. If resistance is not within specifications, replace sensor. Refer to Ambient Temperature Sensor. Ambient Temperature Sensor / Switch HVAC