P0073-AMBIENT AIR TEMPERATURE SENSOR CIRCUIT HIGH

For a complete wiring diagram Refer to Section 8W

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.

Possible Causes

INTERMITTENT DTC

(G31) AAT SIGNAL CIRCUIT SHORTED TO VOLTAGE

(G31) AAT SIGNAL CIRCUIT OPEN OR HIGH RESISTANCE

(G931) AAT SENSOR GROUND CIRCUIT OPEN OR HIGH RESISTANCE

AMBIENT AIR TEMPERATURE SENSOR

POWERTRAIN CONTROL MODULE (PCM)

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Diagnostic Test

1. DTC IS ACTIVE

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

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

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.

With the scan tool, select View DTCs.

Is the status Active for this DTC?

Yes

Go to 2

Refer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)

2. (G31) AAT SIGNAL CIRCUIT SHORTED TO VOLTAGE

Turn the ignition off.
Disconnect the Ambient Air Temperature Sensor connector.
Disconnect the Powertrain Control Module (PCM) 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 PCM Verification Test Ver. 1 (Refer to 9 - ENGINE - STANDARD PROCEDURE).

Go to 3

3. (G31) AAT SIGNAL OPEN OR HIGH RESISTANCE

Turn the ignition off.
Measure the resistance of the (G31) AAT Signal circuit between the Ambient Air Temperature Sensor harness connector and the Powertrain Control Module (PCM) harness connector.

Is the resistance below 5.0 ohms?

Yes

Go to 4

Repair the (G31) AAT Signal circuit for an open circuit or high resistance.
Perform the PCM Verification Test Ver. 1 (Refer to 9 - ENGINE - STANDARD PROCEDURE).

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

Measure the resistance of the (G931) AAT Sensor Ground circuit between the Ambient Air Temperature Sensor harness connector and the Powertrain Control Module (PCM) harness connector.

Is the resistance below 5.0 ohms?

Yes

Go to 5

Repair the (G931) AAT Sensor Ground circuit for an open circuit or high resistance.
Perform the PCM Verification Test Ver. 1 (Refer to 9 - ENGINE - STANDARD PROCEDURE).

5. AMBIENT AIR TEMPERATURE SENSOR

Turn the ignition off.
Connect the Powertrain Control Module (PCM) connector.
Connect a jumper wire between the (G31) AAT Signal circuit and the (G931) AAT 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.

Is the voltage below 1.0 volt with the jumper wire in place?

Yes

Replace the Ambient Air Temperature Sensor in accordance with the Service Information.

Perform the PCM Verification Test Ver. 1 (Refer to 9 - ENGINE - STANDARD PROCEDURE).

Go to 6

6. POWERTRAIN CONTROL MODULE (PCM)

Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Ambient Air Temperature Sensor and the Powertrain Control Module (PCM).
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 PCM Verification Test Ver. 1 (Refer to 9 - ENGINE - STANDARD PROCEDURE).

Replace and program the Powertrain Control Module (PCM) in accordance with the Service Information.
Perform the PCM Verification Test Ver. 1 (Refer to 9 - ENGINE - STANDARD PROCEDURE).