P0072

P0072-AMBIENT AIR TEMPERATURE SENSOR CIRCUIT LOW





For a complete wiring diagram Refer to Diagrams/Electrical.


- When Monitored:
The ignition key on.

- Set Condition:
Ambient Temperature Sensor is less than the minimum acceptable value. One Trip Fault. Three good trips to turn off the MIL.







Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Initial Inspection and Diagnostic Overview .


Diagnostic Test


1. DTC IS ACTIVE
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.


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

With the scan tool, select View DTCs.
Is the DTC Active at this time?

Yes


- Go To 2


No


- Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Intermittent Condition .



2. CHECKING AAT SENSOR
Turn the ignition off.
Disconnect the Ambient Air Temperature Sensor harness connector.
Ignition on, engine not running.
With a scan tool, read the AAT Sensor voltage.

NOTE: The sensor voltage should be approximately 5.0 volts (plus or minus.1 volt) with the connector disconnected.

Does the scan tool display the voltage as described above?

Yes


- Verify that there is good pin to terminal contact in the Sensor and Control Module connectors. Replace the Ambient Air Temperature Sensor if no problems were found with the connectors.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test


No


- Go To 3



3. (G31) AAT SIGNAL CIRCUIT SHORTED TO GROUND




Turn the ignition off.
Disconnect the C5 Totally Integrated Power Module (TIPM) harness connector.
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 short to ground in the (G31) AAT Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test


No


- Go To 4



4. (G31) AAT SIGNAL CIRCUIT SHORTED TO THE (G930) AAT RETURN CIRCUIT




Measure the resistance between the (G930) AAT return circuit and the (G31) AAT Signal circuit in the AAT Sensor harness connector.
Is the resistance below 5.0 ohms?

Yes


- Repair the short between the (G930) AAT return circuit and the (G31) AAT Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test


No


- Go To 5



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




Measure the resistance of the (G31) AAT Signal circuit between the Ambient Air Temperature Sensor harness connector and the C5 TIPM harness connector.
Is the resistance below 5.0 ohms?

Yes


- Go To 6


No


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



6. TOTALLY INTEGRATED POWER MODULE (TIPM)
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the AAT Sensor and the Totally Integrated Power Module (TIPM).
Look for any chafed, pierced, pinched, or partially broken wires.
Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the Sensor and Control Module connectors.
Refer to any Technical Service Bulletins that may apply.
Were there any problems found?

Yes


- Repair as necessary.
- Perform BODY VERIFICATION TEST VER - 1.


No


- Replace and program the TIPM.
- Perform BODY VERIFICATION TEST VER - 1.