P0073
P0073-AMBIENT AIR TEMPERATURE SENSOR CIRCUIT HIGH
For a complete wiring diagram, refer to the Wiring Information.
Theory of Operation
Ambient Air Temperature (AAT) sensor performance looks at the outputs of three temperature sensors and compares them under cold start conditions. The AAT reading is a bussed message from the Totally Integrated Power Module (TIPM) to the Powertrain Control Module (PCM). Following a start to run delay time, the outputs of the ambient, engine coolant and intake air temperature sensors are compared. The AAT sensor is a variable resistor that measures the ambient air temperature. The TIPM supplies a 5 Volt reference and a ground to the sensors low reference signal circuit. When the AAT is low, the sensor resistance is high. When the AAT is high, the sensor resistance is low.
- When Monitored:
With the ignition on and battery voltage greater than 10.4 volts.
- Set Condition:
The Powertrain Control Module (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. Pre-Diagnostic Troubleshooting Procedure.
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.
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.
2. With the scan tool, select View DTCs.
Is the status Active for this DTC?
Yes
- Go To 2
No
- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test.
2. (G31) AAT SIGNAL CIRCUIT SHORTED TO VOLTAGE
1. Turn the ignition off.
2. Disconnect the Ambient Air Temperature Sensor harness connector.
3. Disconnect the Totally Integrated Power Module (TIPM) C4 harness connector.
4. Turn the ignition on.
5. 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 POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Go To 3
3. (G31) AAT SIGNAL OPEN OR HIGH RESISTANCE
1. Turn the ignition off.
2. Measure the resistance of the (G31) AAT Signal circuit between the Ambient Air Temperature Sensor harness connector and the TIPM C4 harness connector.
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 POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
4. (G931) AAT SENSOR GROUND CIRCUIT OPEN OR HIGH RESISTANCE
1. Measure the resistance of the (G931) AAT Sensor Ground circuit between the Ambient Air Temperature Sensor harness connector and the TIPM C4 harness connector.
Is the resistance below 5.0 Ohms?
Yes
- Go To 5
No
- Repair the (G931) AAT Sensor Ground circuit for an open circuit or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
5. AMBIENT AIR TEMPERATURE SENSOR
1. Turn the ignition off.
2. Connect the TIPM C4 harness connector.
3. Connect a jumper wire between the (G31) AAT Signal circuit and the (G931) AAT Sensor Ground in the Ambient Air Temperature Sensor harness connector.
4. Turn the ignition on.
5. 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.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Go To 6
6. TOTALLY INTEGRATED POWER MODULE (TIPM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Ambient Air Temperature Sensor and the TIPM.
2. Look for any chafed, pierced, pinched, or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals.
4. Monitor the scan tool data relative to this circuit and wiggle test the wiring and connectors.
5. Look for the data to change or for the DTC to reset during the wiggle test.
6. Perform any Technical Service Bulletins that may apply.
Were any problems found?
Yes
- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Replace and program the Totally Integrated Power Module (TIPM).
- Perform the BODY VERIFICATION TEST. Body Verification Test.