B0159

CIRCUIT DESCRIPTION
The HVAC control module monitors the outside ambient air temperature via an ambient air temperature sensor. When the air is cold, the sensor resistance and signal voltage are high. When the air is warm, the sensor resistance and signal voltage are low.

CONDITIONS FOR RUNNING THE DTC
The ignition is turned ON.

CONDITIONS FOR SETTING THE DTC
The HVAC control module detects the signal circuit is less than 0.09 V (5 counts) or greater than 4.90 V (250 counts).

ACTION TAKEN WHEN THE DTC SETS
A default value will be used for the sensor data by the HVAC control module. The actual sensor reading will be displayed on the scan tool in the HVAC data list.

CONDITIONS FOR CLEARING THE DTC
- The DTC will become history if the HVAC control module no longer detects a failure.
- The history DTC will clear after 50 fault free ignition cycles.
- The DTC can be cleared with a scan tool.

DIAGNOSTIC AIDS
If condition not present refer to Testing for Intermittent and Poor Connections in Diagrams.

TEST DESCRIPTION

Steps 1-6:

Steps 7-12:

The numbers below refer to the step numbers on the diagnostic table.
2. Scan tool uses a default value, this will not give accurate reading of sensor value if open or short to ground.
8. Tests for the possibility of a short to another 5 V reference circuit.