P0073

P0073-AMBIENT AIR TEMPERATURE SENSOR CIRCUIT HIGH






For a complete wiring diagram refer to: Electrical Diagrams

When Monitored
With the ignition on. Battery voltage greater than 10 volts.

Set Condition
The Ambient Temperature Sensor voltage is greater than 4.98 volts at the PCM for 2.8 seconds. One Trip Fault. Three good trips to turn off the MIL.

Possible Causes
- (G31) AAT SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE
- (G31) AAT SIGNAL CIRCUIT OPEN
- (G931) SENSOR GROUND CIRCUIT OPEN
- AMBIENT AIR TEMPERATURE SENSOR
- FRONT CONTROL MODULE

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.

Diagnostic Test
1. AAT SENSOR VOLTAGE ABOVE 4.98 VOLTS





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

Is the voltage above 4.98 volts?
Yes >> Go To 2
No >> Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

2. AAT SENSOR





Turn the ignition off.
Disconnect the Ambient Air Temperature Sensor harness connector.
Connect a jumper wire between the (G31) AAT Signal circuit and the (G931) Sensor ground circuit in the AAT Sensor harness connector. Ignition on, engine not running.
With a scan tool, read AAT Sensor voltage.

Is the voltage below 1.0 volt with the jumper wire installed?
Yes >> Replace the Ambient Air Temperature Sensor.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No >> Go To 3

NOTE: Remove the jumper wire before continuing.

3. (G31) AAT SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE





Disconnect the C2 FCM harness connector.
Ignition on, engine not running.
Measure the voltage on the (G31) AAT Signal circuit in the AAT Sensor harness connector.

Is the voltage above 5.2 volts?
Yes >> Repair the short to battery voltage in the (G31) AAT Signal circuit.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No >> Go To 4

4. (G31) AAT SIGNAL CIRCUIT OPEN





Turn the ignition off.
Measure the resistance of the (G31) AAT Signal circuit from the AAT Sensor harness connector to the C2 FCM harness connector.

Is the resistance below 5.0 ohms?
Yes >> Go To 5
No >> Repair the open in the (G31) AAT Signal circuit.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

5. (G931) SENSOR GROUND CIRCUIT OPEN





Measure the resistance of the (G931) Sensor ground circuit from the AAT Sensor harness connector to the C2 FCM harness connector.
Is the resistance below 5.0 ohms?
Yes >> Go To 6
No >> Repair the open in the (G931) Sensor ground circuit.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

6. FRONT CONTROL MODULE

NOTE: Before continuing, check the FCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.

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 BODY VERIFICATION TEST VER - 1. Body Verification Test
No >> Replace the Front Control Module per Service Information.
Perform BODY VERIFICATION TEST VER - 1. Body Verification Test