Diagnostic Test

READ AND RECORD DTCS AND ENVIRONMENTAL DATA
NOTE:
After repairing an Ambient Air Temperature (AAT) Sensor circuit, or replacing the AAT Sensor, the vehicle MUST be driven above 15 mph (24 km/h), for at least five minutes. Performing this allows the AAT Sensor data in the BCM to be updated. Failure to perform this may lead to the incorrect replacement of the BCM.
1. Turn the ignition on.
2. With the scan tool, read DTCs in all Electronic Control Units (ECUs) and record on the repair order.
3. With the scan tool, run a vehicle Scan Report, or record the Environmental Data related to the DTCs.
4. With the scan tool, read Body Control Module (BCM) DTCs.
Is the DTC Active?

Yes
- Go To 2
No
- Perform the appropriate INTERMITTENT CONDITION diagnostic procedure. Refer to TESTING FOR AN INTERMITTENT CONDITION .
CHECK THE AMBIENT AIR TEMPERATURE (AAT) SENSOR FOR AN INTERNAL SHORT
NOTE:
Additional DTCs may set when the harness connector is disconnected and the ignition is positioned on. After all repairs are completed, make sure to erase any additional DTCs that may have set.

NOTE:
The AAT Sensor operates between 345, 260 Ohms (low temperature) and 181 Ohms (high temperature).

At 20°C (68°F) the AAT Sensor resistance should be between 11, 370 Ohms and 13, 610 Ohms.
1. Turn the ignition off.
2. Disconnect the Ambient Air Temperature (AAT) Sensor harness connector.
3. Turn the ignition on.
4. With the scan tool, read BCM DTCs.
  Is the DTC Active?
  
  Yes
  - Go To 3
  No
  - Replace the Ambient Air Temperature (AAT) Sensor in accordance with the Service Information. Refer to SENSOR, AMBIENT TEMPERATURE, REMOVAL AND INSTALLATION .
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
DISCONNECT THE BCM HARNESS CONNECTOR(S) AND CHECK THE (G31) AAT SENSOR SIGNAL CIRCUIT FOR A SHORT TO GROUND
1. The ignition must be off when checking a circuit for continuity to ground.
2. Disconnect all Electronic Control Unit (ECU) and component harness connectors containing the circuit being tested. Note: Use the wiring diagram as a guide to follow the path of the circuit.
3. Connect the negative lead of the DVOM to a known good ground.
4. Connect the positive lead of the DVOM to the circuit being tested at the ECU or component harness connector and check for continuity between the circuit and ground.
NOTE:
When probing a circuit at any harness connector, always use an appropriate probing tool to prevent any possible damage to the harness connector terminals.

NOTE:
There should be no continuity between ground and the circuit being tested.

Is there continuity between ground and the circuit being tested?

Yes
- Repair the circuit for a short to ground. Use the wiring diagram as a guide to trace the circuit and look for any in-line connectors to help isolate the location of the short.
- Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
No
- Go To 4
CHECK THE (G31) AAT SENSOR SIGNAL CIRCUIT FOR A SHORT TO THE (G931) SENSOR GROUND CIRCUIT
1. The ignition must be off when checking a circuit for continuity.
2. Connect the negative lead of the DVOM to one of the circuits being tested at the ECU or component harness connector.
3. Connect the positive lead of the DVOM to the other circuit being tested at the ECU or component harness connector and check for continuity between the circuits.
NOTE:
When probing a circuit at any harness connector, always use an appropriate probing tool to prevent any possible damage to the harness connector terminals.

NOTE:
There should be no continuity between the circuits being tested.

Is there continuity between the circuits being tested?

Yes
- Repair the short between the circuits.
- Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
No
- Go To 5
DISCONNECT RELATED MODULE HARNESS CONNECTIONS AND INSPECT FOR PROBLEMS
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.
  - Perform a terminal drag test on each connector terminal to verify proper terminal tension.
  Repair any conditions that are found.
5. Connect all BCM harness connectors. Be certain that all harness connectors are fully seated and the connector locks are fully engaged.
6. Connect all in-line harness connectors (if equipped). Be certain that all connectors are fully seated and the connector locks are fully engaged.
7. Connect 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. Using the recorded Environmental Data, along with the When Monitored and Set Conditions above, operate the vehicle in the conditions that set the DTC.
10. With the scan tool, read BCM DTCs.
  Did the DTC return?
  
  Yes
  - Replace the Body Control Module (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
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  - Test complete.