P0072

P0072-AMBIENT AIR TEMPERATURE SENSOR CIRCUIT LOW







- When Monitored:
The ignition key on.

- Set Condition:
Ambient Temperature Sensor is less than 0.078 of a volt at the Engine Control Module (ECM) for 2.8 seconds. One Trip Fault. Three good trips to turn off the MIL.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

1. AAT SENSOR VOLTAGE BELOW 0.078 OF A VOLT

NOTE: Diagnose any CAN - C Communication DTCs before continuing.

1. Ignition on, engine not running.
2. With a scan tool, read the Ambient Air Temperature Sensor voltage.

Is the voltage below 0.078 of a volt?

Yes

- Go To 2

No

- Perform the INTERMITTENT CONDITION - DIESEL diagnostic procedure. Intermittent Condition Test.

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

Is the voltage above 4.6 volts?

Yes

- Replace the Ambient Temperature Sensor.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 3

3. (G31) AAT SIGNAL CIRCUIT SHORTED TO GROUND




1. Turn the ignition off.
2. Disconnect the C5 Totally Integrated Power Module (TIPM) harness connector.
3. 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) SENSOR GROUND CIRCUIT




1. 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. TOTALLY INTEGRATED POWER MODULE

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 wire harness and connectors. Pay particular attention to all Power and Ground circuits.

Were there any problems found?

Yes

- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Replace and program the TIPM.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.