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 C6 harness connector.
4. Measure the resistance of the (G31) AAT Signal circuit between the AAT Sensor harness connector and the BCM C6 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 C6 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 .
CHECK THE ABILITY OF THE BCM TO READ THE AAT SENSOR SIGNAL
1. Turn the ignition off.
2. Connect the BCM C6 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
CHECK RELATED HARNESS CONNECTIONS
1. Disconnect all BCM harness connectors.
2. Disconnect all related in-line harness connections (if equipped).
3. Disconnect the related component harness connectors.
4. Inspect harness connectors, component connectors, and all male and female terminals for the following conditions:
  - Proper connector installation.
  - Damaged connector locks.
  - Corrosion.
  - Other signs of water intrusion.
  - Weather seal damage (if equipped).
  - Bent terminals.
  - Overheating due to a poor connection (terminal may be discolored due to excessive current draw).
  - Terminals that have been pushed back into the connector cavity.
  - Check for spread terminals and verify proper terminal tension.
  Repair any conditions that are found.
5. Reconnect all BCM harness connectors. Be certain that all harness connectors are fully seated and the connector locks are fully engaged.
6. Reconnect all in-line harness connectors (if equipped). Be certain that all connectors are fully seated and the connector locks are fully engaged.
7. Reconnect all related component harness connectors. Be certain that all connectors are fully seated and the connector locks are fully engaged.
8. With the scan tool, erase DTCs.
9. Test drive or operate the vehicle in accordance with the when monitored and set conditions.
10. With the scan tool, read DTCs.
  Did the DTC return?
  
  Yes
  - Replace the BCM in accordance with the Service Information. Refer to MODULE, BODY CONTROL (BCM), REMOVAL AND INSTALLATION .
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  No
  - Repair the poor connections.
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .