Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Diagnostic Test
- ACTIVE DTC NOTE:
Diagnose any CAN - C Communication DTCs before continuing.
- Turn the ignition off.
- If possible, allow the vehicle to sit with the ignition off for more than 480 minutes in an environment where the temperature is consistent and above - 64°C (-83.2°F).
- Turn the ignition on.
- With a scan tool, compare the AAT, ECT, and IAT sensor values.
Is the Ambient Air Temperature Sensor value within 15°C (59°F) of the other two sensor values?
Yes
- Go To 2
No
- Perform the INTERMITTENT CONDITION diagnostic procedure. Refer to INTERMITTENT CONDITION .
- CHECK FOR HIGH RESISTANCE IN THE (G31) AAT SENSOR SIGNAL CIRCUIT
- Disconnect the Ambient Air Temperature Sensor harness connector.
- Disconnect the BCM C6 harness connector.
- Measure the resistance of the (G31) AAT Sensor Signal circuit between the Ambient Air Temperature Sensor harness connector and the BCM C6 harness connector.
Is the resistance below 5.0 Ohms?
Yes
- Go To 3
No
- Repair the (G31) AAT Sensor 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
- Measure the resistance of the (G931) AAT Sensor Ground circuit between the Ambient Air Temperature Sensor harness connector and the BCM C6 harness connector.
Is the resistance below 5.0 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 .
- Measure the resistance of the (G931) AAT Sensor Ground circuit between the Ambient Air Temperature Sensor harness connector and the BCM C6 harness connector.
- AMBIENT AIR TEMPERATURE SENSOR
- Turn the ignition off.
- Reconnect the BCM C6 harness connector.
- Connect a jumper between the (G931) AAT Sensor Ground circuit and the (G31) AAT Sensor Signal circuit in the Ambient Air Temperature Sensor harness connector.
- Turn the ignition on.
- With the scan tool, read the Ambient Air Temperature Sensor signal voltage.
Is the voltage below 0.1 volt with the jumper in place?
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)
- Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Ambient Air Temperature Sensor and the Body Control Module (BCM).
- Look for any chafed, pierced, pinched, or partially broken wires.
- Look for broken, bent, pushed out or corroded terminals.
- Monitor the scan tool data relative to this circuit and wiggle test the wiring and connectors.
- Look for the data to change or for the DTC to reset during the wiggle test.
- Perform any Technical Service Bulletins that may apply.
Were any problems found?
Yes
- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
No
- Replace the Body Control Module (BCM) in accordance with the service information. Refer to MODULE, BODY CONTROL, REMOVAL .
- Perform the BODY VERIFICATION TEST. Refer to STANDARD PROCEDURE .
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.