P0073

P0073-AMBIENT AIR TEMPERATURE SENSOR CIRCUIT HIGH





For complete wiring diagrams refer to Diagrams/Electrical.


- When Monitored:

With the ignition on and battery voltage greater than 10.4 volts.

- Set Condition:

The PCM detects that the Ambient Air Temperature Sensor input voltage is above the maximum acceptable value.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.

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 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 VOLTAGE





Turn the ignition off.
Disconnect the Ambient Air Temperature Sensor connector.
Disconnect the Front Control Module (FCM) connector.
Turn the ignition on.
Measure the voltage of the (G31) AAT Signal circuit in the Ambient Air Temperature Sensor harness connector.

Is there any voltage present?

Yes

- Repair the (G31) AAT Signal circuit for a short to voltage.
- Perform the Body Verification Test Ver. 1. Body Verification Test

No

- Go to 3

3. (G31) AAT SIGNAL OPEN OR HIGH RESISTANCE





Turn the ignition off.

CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals, resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis.

Measure the resistance of the (G31) AAT Signal circuit between the Ambient Air Temperature Sensor harness connector and the appropriate terminal of special tool #8815.

Is the resistance below 5.0 ohms?

Yes

- Go to 4

No

- Repair the (G31) AAT Signal circuit for an open circuit or high resistance.
- Perform the Body Verification Test Ver. 1. Body Verification Test

4. (G931) SENSOR GROUND CIRCUIT OPEN OR HIGH RESISTANCE






CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals, resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis.

Measure the resistance of the (G931) Sensor Ground circuit between the Ambient Air Temperature Sensor harness connector and the appropriate terminal of special tool #8815.

Is the resistance below 5.0 ohms?

Yes

- Go to 5

No

- Repair the (G931) Sensor Ground circuit for an open circuit or high resistance.
- Perform the Body Verification Test Ver. 1. Body Verification Test

5. AMBIENT AIR TEMPERATURE SENSOR





Turn the ignition off.
Connect the Front Control Module (FCM) connector.
Connect a jumper wire between the (G31) AAT Signal circuit and the (G931) Sensor Ground in the Ambient Air Temperature Sensor harness connector.
Turn the ignition on.
With the scan tool, read the Ambient Air Temperature Sensor signal voltage.

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

Does the scan tool display the voltage as described above?

Yes

- Replace the Ambient Air Temperature Sensor.
- Perform the Body Verification Test Ver. 1. Body Verification Test

No

- Go to 6

6. FRONT CONTROL MODULE (FCM)

Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Ambient Air Temperature Sensor and the Front Control Module (FCM).
Look for any chafed, pierced, pinched, or partially broken wires.
Look for broken, bent, pushed out or corroded terminals.
Monitor the scan tool data relative to this circuit and wiggle test the wiring and connectors.
Look for the data to change or for the DTC to reset during the wiggle test.
Refer to any Technical Service Bulletins that may apply.

Were any problems found?

Yes

- Repair as necessary.
- Perform the Body Verification Test Ver. 1. Body Verification Test

No

- Replace and program the Front Control Module (FCM).
- Perform the Body Verification Test Ver. 1. Body Verification Test