P0073-AMBIENT AIR TEMPERATURE SENSOR CIRCUIT HIGH
For a complete wiring diagram, refer to the Wiring Information.
Theory of Operation
The Ambient Air Temperature Sensor is a two wire sensor that is hard wired to the Totally Integrated Power Module (TIPM). The TIPM supplies a 5 Volt sensor signal and sensor ground to the Ambient Air Temperature Sensor. The sensor internal resistance changes in response to changes in ambient temperature. The TIPM provides the Powertrain Control Module (PCM) with ambient temperature over the CAN Bus network.
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When Monitored:
With the ignition on. Battery voltage greater than 10 Volts.
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Set Condition:
The Ambient Air Temperature Sensor voltage is greater than the maximum allowable voltage for 0.5 second. One Trip Fault. Three good trips to turn off the MIL.
Possible Causes |
|---|
| (G31) AAT SIGNAL CIRCUIT SHORTED TO VOLTAGE |
| (G31) AAT SIGNAL CIRCUIT OPEN/HIGH RESISTANCE |
| (G931) SENSOR GROUND CIRCUIT OPEN/HIGH RESISTANCE |
| AMBIENT AIR TEMPERATURE (AAT) SENSOR |
| TOTALLY INTEGRATED POWER MODULE (TIPM) |
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
| NOTE: | Diagnose any CAN C Bus Communication DTCs before continuing. |
| 1. | Turn the ignition one. |
| 2. | With the scan tool, select View DTCs. |
Is the DTC active?
Yes
- Go To 2
No
- Perform the INTERMITTENT DTC diagnostic procedure. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
2. CHECK THE (G31) AAT SIGNAL CIRCUIT FOR A SHORT TO VOLTAGE
 |
| 1. | Turn the ignition off. |
| 2. | Disconnect the Ambient Air Temperature Sensor (AAT) harness connector. |
| 3. | Disconnect the C4 TIPM harness connector. |
| 4. | Turn the ignition on, engine not running. |
| 5. | Measure the voltage on the (G31) AAT Signal circuit in the AAT 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. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
No
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Go To 3
3. CHECK THE (G31) AAT SIGNAL CIRCUIT FOR AN OPEN/HIGH RESISTANCE
 |
| 1. | Turn the ignition off. |
| 2. | Measure the resistance of the (G31) AAT Signal circuit between the AAT Sensor harness connector and the C4 TIPM harness connector. |
Is the resistance below 5.0 Ohms?
Yes
- Go To 4
No
- Repair the (G31) AAT Signal circuit for an open or high resistance.
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Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM)
- Standard Procedure).
4. CHECK THE (G931) SENSOR GROUND CIRCUIT FOR AN OPEN/HIGH RESISTANCE
 |
| 1. | Measure the resistance of the (G931) Sensor Ground circuit from the AAT Sensor harness connector to the C4 TIPM harness connector. |
Is the resistance below 5.0 Ohms?
Yes
- Go To 5
No
- Repair the (G931) Sensor Ground circuit for an open or high resistance.
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Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM)
- Standard Procedure).
 |
| 1. | Reconnect the C4 TIPM harness connector. |
| 2. | Connect a jumper wire between the (G31) AAT Signal circuit and the (G931) Sensor Ground circuit in the AAT Sensor harness connector. |
| 3. | Turn the ignition on, engine not running. |
| 4. | With a scan tool, select View DTCs. |
| NOTE: | The scan tool should display the P0072-AMBIENT AIR TEMPERATURE SENSOR CIRCUIT LOW DTC with the jumper in place. |
Does the scan tool display the voltage as described above?
Yes
- Verify that there is good pin to terminal contact in the AAT Sensor and Totally Integrated Power Module (TIPM) connectors. If ok, replace the Ambient Air Temperature Sensor.
- Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
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 AAT Sensor and the Totally Integrated Power Module (TIPM). |
| 2. | Look for any chafed, pierced, pinched or partially broken wires. |
| 3. | Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the AAT Sensor and Totally Integrated Power Module connectors. |
| 4. | Perform any Technical Service Bulletins that may apply. |
Were there any problems found?
Yes
- Repair as necessary.
- Perform the BODY VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Totally Integrated Power (TIPM) - Standard Procedure).
No
- Replace the Totally Integrated Power Module (TIPM) in accordance with the service information.
- Perform the BODY VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Totally Integrated Power (TIPM) - Standard Procedure).