P0073-AMBIENT AIR TEMPERATURE SENSOR CIRCUIT HIGH
For a complete wiring diagram Refer to Section 8W.
- 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. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).
Diagnostic Test
1. AAT SENSOR VOLTAGE ABOVE 4.98 VOLTSIgnition on, engine not running.
With a scan tool, read the Ambient Air Temperature Sensor voltage.
Is the voltage above 4.98 volts?
Yes
- Go To2
No
- Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
- Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
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 the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No
- Go To 3
NOTE: Remove the jumper wire before continuing.
3. (G31) AAT SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE
Turn the ignition off.
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 0 volts?
Yes
- Repair the short to battery voltage in the (G31) AAT Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
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 the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
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 the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
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. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE)
No
- Replace the Front Control Module per Service Information.
- Perform BODY VERIFICATION TEST. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE)