P0071
P0071-AMBIENT AIR TEMPERATURE SENSOR PERFORMANCE
For a complete wiring diagram, refer to the Wiring Information.
Theory of Operation
The PCM compares engine coolant temperature (ECT), intake air temperature (IAT), and ambient air temperature (AAT) under cold start conditions. Following a start to run delay time, the sensor values are compared. If the one sensor value is not within a specified range of the other two sensors, the value is determined to be irrational.
- When Monitored:
With engine off time greater than 480 minutes and ambient temperature greater than - 7° C (19.4° F).
- Set Condition:
After a calibrated amount of cool down time, the PCM compares the AAT, ECT, and IAT Sensor values. If one sensor value is not within 10° C (18° F) of the other temperature sensors for two consecutive trips, a DTC will set. Three good trips to turn off the MIL.
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.
1. DTC IS ACTIVE
NOTE: Diagnose any CAN - C Communication DTCs before continuing.
NOTE: Diagnose and repair any system voltage DTCs before continuing with this test.
1. Turn the ignition off.
2. 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 - 7° C (19.4° F).
3. Test drive the vehicle. The vehicle must exceed 48 km/h (30 mph) during the test drive. Do not cycle the ignition off when the test drive is completed.
4. With a scan tool, select View DTCs.
Does the scan tool display this DTC as active?
Yes
- Go To 3
No
- Go To 2
2. AMBIENT AIR TEMPERATURE
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 to intake air 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
- Refer to CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure. Intermittent Condition Test
No
- Go To 3
3. AAT SENSOR
1. Turn the ignition off.
2. Disconnect the AAT Sensor harness connector.
3. Connect a jumper wire between the (G31) AAT Signal circuit and the (G931) AAT Return circuit in the AAT harness connector.
4. Turn the ignition on.
5. With a scan tool, read the AAT voltage.
Is the voltage below 1.0 volt with the jumper wire installed?
Yes
- Replace the AAT Sensor.
- Perform the PCM VERIFICATION TEST. Powertrain Verification Test
No
- Go To 4
4. (G31) AAT SIGNAL CIRCUIT SHORTED TO VOLTAGE
1. Turn the ignition off.
2. Disconnect the C2 TIPM harness connector.
3. Turn the ignition on.
4. Measure the voltage on the (G31) AAT Signal circuit in the AAT Sensor harness connector.
Is voltage present?
Yes
- Repair the (G31) AAT Signal circuit for a short to voltage.
- Perform the PCM VERIFICATION TEST. Powertrain Verification Test
No
- Go To 5
5. (G31) AAT SIGNAL CIRCUIT OPEN OR HIGH RESISTANCE
1. Turn the ignition off.
2. Measure the resistance of the (G31) AAT Signal circuit between the AAT Sensor harness connector and the C2 TIPM harness connector.
Is the resistance below 5.0 ohms?
Yes
- Go To 6
No
- Repair the (G31) AAT Signal circuit for an open.
- Perform the PCM VERIFICATION TEST. Powertrain Verification Test
6. (G931) SENSOR GROUND CIRCUIT OPEN OR HIGH RESISTANCE
1. Measure the resistance of the (G931) Sensor Ground circuit between the AAT Sensor harness connector and the C2 TIPM harness connector.
Is the resistance below 5.0 ohms?
Yes
- Go To 7
No
- Repair the (G931) Sensor Ground circuit for an open.
- Perform the PCM VERIFICATION TEST. Powertrain Verification Test
7. (G31) AAT SIGNAL CIRCUIT SHORTED GROUND
1. Measure the resistance between ground and the (G31) AAT Signal circuit in the AAT Sensor harness connector.
Is the resistance below 100 ohms?
Yes
- Repair the (G31) AAT Signal circuit for a short to ground.
- Perform the PCM VERIFICATION TEST. Powertrain Verification Test
No
- Go To 8
8. (G31) AAT SIGNAL CIRCUIT SHORTED TO THE (G931) SENSOR GROUND CIRCUIT
1. Measure the resistance between the (G931) Sensor Ground circuit and the (G31) AAT Signal circuit in the AAT Sensor harness connector.
Is the resistance below 5.0 ohms?
Yes
- Repair the (G931) Sensor Ground circuit for a short to the (G31) AAT Signal circuit.
- Perform the PCM VERIFICATION TEST. Powertrain Verification Test
No
- Go To 9
9. TOTALLY INTEGRATED POWER MODULE (TIPM)
NOTE: Before continuing, check the TIPM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.
1. Using the schematics as a guide, inspect the electrical harness and connectors. Pay particular attention to all Power and Ground circuits.
Were there any problems found?
Yes
- Repair as necessary.
- Perform the PCM VERIFICATION TEST. Powertrain Verification Test
No
- Replace the Totally Integrated Power Module (TIPM).
- Perform the BODY VERIFICATION TEST. Body Verification Test