P0072

P0072-AMBIENT AIR TEMPERATURE SENSOR CIRCUIT LOW







- When Monitored:
With the engine running and battery voltage greater than 10 volts.

- Set Condition:
The PCM detects that the sensor input voltage is below the minimum acceptable value.





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 with this test.

NOTE: Diagnose and repair any system voltage DTCs before continuing with this test.

1. Start the engine and allow it to reach normal operating temperature.

WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.

2. With the scan tool, select View DTCs.

Is the status Active for this DTC?

Yes

- Go To 2

No

- Refer to the CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure. Checking for an Intermittent DTC.

2. (G31) AAT SIGNAL CIRCUIT SHORTED TO GROUND




1. Turn the ignition off.
2. Disconnect the Ambient Air Temperature Sensor harness connector.
3. Disconnect the C4 Totally Integrated Power Module harness connector.
4. Measure the resistance between ground and the (G31) AAT Signal circuit in the Ambient Air Temperature Sensor harness connector.

Is the resistance above 100 ohms?

Yes

- Go To 3

No

- Repair the short to ground in the (G31) AAT Signal circuit.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

3. (G31) AAT SIGNAL CIRCUIT SHORTED TO THE (G931) AAT RETURN CIRCUIT




1. Measure the resistance between the (G31) AAT Signal circuit and the (G931) AAT Return circuit in the Ambient Air Temperature Sensor harness connector.

Is the resistance above 100 ohms?

Yes

- Go To 4

No

- Repair the short between the (G31) AAT Signal circuit and the (G931) AAT Return circuit.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

4. EXCESSIVE RESISTANCE IN THE (G31) AAT SIGNAL CIRCUIT





NOTE: When checking circuits at the Totally Integrated Power Module, be careful not to damage or distort the connector terminals. Improper measurement technique could result in poor pin to terminal contact.

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

Is the resistance below 5.0 ohms?

Yes

- Go To 5

No

- Repair the excessive resistance in the (G31) AAT Signal circuit.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

5. AMBIENT AIR TEMPERATURE SENSOR SIGNAL VOLTAGE
1. Turn the ignition off.
2. Connect the C4 Totally Integrated Power Module harness connector.
3. Turn the ignition on.
4. With the scan tool, read the Ambient Air Temperature Sensor signal voltage.

NOTE: The voltage should be approximately 5.0 volts with the connector disconnected.

Is the voltage as described with the connector disconnected?

Yes

- Go To 6

No

- Go To 7

6. AMBIENT AIR TEMPERATURE SENSOR
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Ambient Air Temperature Sensor and the Totally Integrated Power Module.
2. Look for any chafed, pierced, pinched, or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the related connectors.
4. Monitor the scan tool data relative to this circuit and wiggle test the wiring and connectors.
5. Look for the data to change or for the DTC to reset during the wiggle test.
6. Search for any Technical Service Bulletins that may apply.

Were any problems found?

Yes

- Repair as necessary.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

No

- Replace the Ambient Air Temperature Sensor.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

7. TOTALLY INTEGRATED POWER MODULE
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Ambient Air Temperature Sensor and the Totally Integrated Power Module.
2. Look for any chafed, pierced, pinched, or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the related connectors.
4. Monitor the scan tool data relative to this circuit and wiggle test the wiring and connectors.
5. Look for the data to change or for the DTC to reset during the wiggle test.
6. Search for any Technical Service Bulletins that may apply.

Were any problems found?

Yes

- Repair as necessary.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

No

- Replace the Totally Integrated Power Module.
- Perform the BODY VERIFICATION TEST. Body Verification Test.