Powertrain Control Module (PCM)

P0073-AMBIENT AIR TEMPERATURE SENSOR CIRCUIT HIGH





For a complete wiring diagram, refer to the Wiring Information Electrical Diagrams.

- When Monitored:
With the ignition on. Battery voltage greater than 10 Volts.

- Set Condition:
The Ambient Temperature (AAT) sensor voltage is greater than maximum allowable voltage. One Trip Fault. Three good trips to turn off the Malfunction Indicator Lamp (MIL).





WARNING: On vehicles equipped with the high voltage system, you must thoroughly read and follow all High Voltage Safety procedures. In addition, before performing any diagnostic or service procedure near a high voltage component, you must perform the High Voltage Power Down. Failure to follow these instructions may result in possible serious or fatal injury

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

1. ACTIVE Diagnostic Trouble Code (DTC)
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 may result in possible serious or fatal injury.

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

2. 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 Test.

2. AAT SENSOR




1. Turn the ignition off.
2. Disconnect the AAT sensor electrical connector.
3. Connect a jumper wire between the (G31) AAT signal circuit and the (G931) sensor ground circuit in the AAT sensor electrical connector.
4. Ignition on, engine not running.
5. With the scan tool, read AAT sensor voltage.

NOTE: The sensor voltage should be approximately 0 Volt (plus or minus 0.1 volt) with the jumper wire in place.

Does the scan tool display the voltage as described above?

Yes

- Verify there is good pin to terminal contact in the AAT sensor and Front Control Module (FCM) electrical connectors. Replace the AAT sensor if no problems were found with the connectors.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 3 NOTE: Remove the jumper wire before continuing.


3. (G31) AAT SIGNAL CIRCUIT SHORTED TO VOLTAGE




1. Turn the ignition off.
2. Disconnect the FCM C2 electrical connector.
3. Ignition on, engine not running.
4. Measure the voltage on the (G31) AAT signal circuit in the AAT sensor electrical connector.

Is there any voltage present?

Yes

- Repair the short to voltage in the (G31) AAT signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

No

- Go To 4

4. (G31) AAT SIGNAL CIRCUIT OPEN




1. Turn the ignition off.
2. Measure the resistance of the (G31) AAT signal circuit from the AAT sensor electrical connector to the FCM C2 electrical connector.

Is the resistance less than 5 ohms?

Yes

- Go To 5

No

- Repair the open in the (G31) AAT signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

5. (G931) SENSOR GROUND CIRCUIT OPEN




1. Measure the resistance of the (G931) sensor ground circuit from the AAT sensor electrical connector to the FCM C2 electrical connector.

Is the resistance less than 5 ohms?

Yes

- Go To 6

No

- Repair the open in the (G931) sensor ground circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

6. FRONT CONTROL MODULE (FCM)
1. With the wiring diagram/schematic as a guide, inspect the wiring and connectors between the AAT sensor and the FCM.
2. Look for any chafed, pierced, pinched, or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals. Verify there is good pin to terminal contact in the AAT sensor and FCM connectors.
4. Search for any Technical Service Bulletins (TSBs) that may apply.

Were there any problems found?

Yes

- Repair as necessary.
- Perform BODY VERIFICATION TEST VER - 1. Body Verification Test.

No

- Replace the FCM.
- Perform BODY VERIFICATION TEST VER - 1. Body Verification Test.