P0071-AMBIENT AIR TEMPERATURE SENSOR PERFORMANCE

For a complete wiring diagram Refer to Section 8W

When Monitored:
With the ignition on.
Set Condition:
The Ambient Air Temperature Sensor signal is implausible for 0.5 second.

Possible Causes

(G31) AMBIENT AIR TEMP SENSOR SIGNAL CIRCUIT SHORTED TO VOLTAGE

(G31) AMBIENT AIR TEMP SENSOR SIGNAL CIRCUIT SHORTED TO GROUND

(G931) AMBIENT AIR TEMP SENSOR GROUND CIRCUIT OPEN

(G31) AMBIENT AIR TEMP SENSOR SIGNAL CIRCUIT OPEN

AMBIENT TEMPERATURE SENSOR

TOTALLY INTEGRATED POWER MODULE

Diagnostic Test

1. CHECK FOR ACTIVE DTC

NOTE: If the ECM detects and stores a DTC, the ECM also stores the engine/vehicle operating conditions under which the DTC was set. Some of these conditions are displayed on the scan tool at the same time the DTC is displayed.

NOTE: Before erasing stored DTCs, record these conditions. Attempting to duplicate these conditions may assist when checking for an active DTC.

Turn the ignition on.
With the scan tool, erase TIPM DTCs.
Turn the ignition off for 10 seconds.
Turn the ignition on.
Monitor the scan tool for TIPM DTCs.

Did this DTC set again?

Yes

Go To 2

Refer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)

2. (G31) AMBIENT AIR TEMP SENSOR SIGNAL CIRCUIT SHORTED TO VOLTAGE

Turn the ignition off.
Disconnect the Ambient Air Temperature Sensor harness connector.
Disconnect the TIPM C4 harness connector.
Remove the Main Relay.
Connect a jumper wire between cavity B7 and cavity B9 of the Main Relay connector.
Turn the ignition on.
Measure the voltage on the (G31) Ambient Air Temperature Sensor Signal circuit at the AAT Sensor harness connector.

NOTE: Remove the jumper wire.

Is the voltage below 1.0 volt?

Yes

Go To 3

Repair the (G31) Ambient Air Temperature Sensor Signal circuit for a short to voltage.
Perform the ECM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).

3. (G31) AMBIENT AIR TEMP SENSOR SIGNAL CIRCUIT OPEN

Turn the ignition off.
Measure the resistance of the (G31) Ambient Air Temperature Sensor Signal circuit between the AAT Sensor harness connector and Totally Integrated Power Module C4 harness connector.

Is the resistance below 10.0 ohms?

Yes

Go To 4

Repair the (G31) Ambient Air Temperature Sensor Signal circuit for an open.
Perform the ECM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).

4. (G31) AMBIENT AIR TEMP SENSOR SIGNAL CIRCUIT SHORTED TO GROUND

Turn the ignition off.
Measure the resistance between ground and the (G31) Ambient Air Temperature Sensor Signal circuit at the AAT Sensor harness connector.

Is the resistance above 1000 ohms?

Yes

Go To 5

Repair the (G31) Ambient Air Temperature Sensor Signal circuit for a short to ground.
Perform the ECM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).

5. AMBIENT AIR TEMPERATURE SENSOR

Turn the ignition off.
Connect a jumper wire between the (G31) Ambient Air Temperature Sensor Signal and the (G931) Sensor Ground circuit in the Ambient Air Temperature Sensor harness connector.
Turn the ignition on.
Monitor the scan tool for TIPM DTCs.

Does the scan tool display P0072 AMB TEMP. SENSOR CIRCUIT SIGNAL VOLTAGE TOO LOW?

Yes

Replace the Ambient Air Temperature Sensor.

Perform the ECM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).

Go To6

6. (G931) AMBIENT AIR TEMP SENSOR GROUND CIRCUIT OPEN

Turn the ignition off.
Disconnect the TIPM harness connectors.
Measure the resistance of the (G931) Ambient Air Temp Sensor Ground circuit between the TIPM harness connector and the Ambient Air Temperature Sensor harness connector.

Is the resistance below 10.0 ohms?

Yes

Replace and program the Totally Integrated Power Module in accordance with the Service Information.

Perform the ECM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).

Repair the (G931) Ambient Air Temperature Sensor Ground circuit for an open.
Perform the ECM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).