Diagnostic Test

CHECK FOR AN ACTIVE CONDITION
1. Turn the ignition off.
2. Allow the vehicle to sit with the ignition off in an environment where the temperature is consistent and above - 7°C (19.4°F) until the engine coolant temperature is equal or close to ambient temperature.
3. Turn the ignition on.
4. With a scan tool, compare the AAT, ECT, and IAT sensor values.
  Is the AAT Sensor value within 10°C (18°F) of the other two sensor values?
  
  Yes
  - Perform the INTERMITTENT CONDITION diagnostic procedure. Refer to INTERMITTENT CONDITION .
  No
  - Go To 2
CHECK FOR HIGH RESISTANCE IN THE (G31) AAT SIGNAL CIRCUIT
1. Turn the ignition off.
2. Disconnect the AAT Sensor harness connector.
3. Disconnect the BCM D harness connector.
4. Measure the resistance of the (G31) AAT Signal circuit between the AAT Sensor harness connector and the BCM D harness connector.
  Is the resistance below 3.0 Ohms?
  
  Yes
  - Go To 3
  No
  - Repair the (G31) AAT Signal circuit for an open or high resistance.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
CHECK FOR HIGH RESISTANCE IN THE (G931) AAT SENSOR GROUND CIRCUIT
1. Measure the resistance of the (G931) AAT Sensor Ground circuit between the AAT Sensor harness connector and the BCM D harness connector.
  Is the resistance below 3.0 Ohms?
  
  Yes
  - Go To 4
  No
  - Repair the (G931) AAT Sensor Ground for an open or high resistance.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
AMBIENT AIR TEMPERATURE SENSOR
1. Turn the ignition off.
2. Reconnect the BCM D harness connector.
3. Turn the ignition on.
4. With the scan tool, read DTCs.
  NOTE:
  The P0073-AAT SENSOR CIRCUIT HIGH DTC should display as active or pending with the AAT harness connector disconnected.
5. Connect a jumper between the (G31) AAT Signal circuit and the (G931) AAT Sensor Ground circuit at the AAT Sensor harness connector.
  NOTE:
  The P0072-AAT SENSOR CIRCUIT LOW DTC should display as active or pending with the jumper in place.
  
  Do the DTCs display as described above?
  
  Yes
  - Replace the Ambient Air Temperature Sensor in accordance with the Service Information.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Go To 5
BODY CONTROL MODULE (BCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the AAT Sensor and the Body Control Module (BCM).
2. Look for any chafed, pierced, pinched, or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals.
4. Monitor the scan tool data relative to this circuit and wiggle test the wiring and connectors.
5. Look for the data to change or for the DTC to reset during the wiggle test.
6. Perform any Service Bulletins that may apply.
  Were any problems found?
  
  Yes
  - Repair as necessary.
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  No
  - Replace the Body Control Module (BCM) in accordance with the Service Information. Refer to MODULE, BODY CONTROL (BCM), REMOVAL .
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .