P0072
P0072 - Ambient Air Temperature Sensor Circuit Low
For wiring diagrams, refer to.
• When Monitored: With the engine running and battery voltage greater than 10 volts.
• Set Condition: The PCM detects that the sensor input voltage is less than the minimum acceptable value.
• Always perform the pre-diagnostic troubleshooting procedure before proceeding. Refer to => Non-DTC Based Diagnostics. Pre-Diagnostic Troubleshooting Procedure
Test Step 1 - DTC is Active
• Diagnose any CAN C communication DTCs before continuing with this test.
• Diagnose and repair any system voltage DTCs before continuing with this test.
• Start the engine and allow it to reach normal operating temperature.
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 Test Step 2 => [ Test
Step 2 - AAT Signal Circuit Shorted to Ground ]
No
• Refer to the checking for an intermittent DTC diagnostic procedure. Refer => Non-DTC Based Diagnostics.
Test Step 2 - AAT Signal Circuit Shorted to Ground
• Turn the ignition OFF.
• Disconnect the ambient air temperature sensor harness connector.
• Disconnect the C4 totally integrated power module harness connector.
• Measure the resistance between ground and the AAT signal circuit in the ambient air temperature sensor harness connector.
Is the resistance more than 100 ohms?
Yes
• Go to Test Step 3 => [ Test
Step 3 - AAT Signal Circuit Shorted to the AAT Return Circuit ]
No
• Repair the short to ground in the AAT signal circuit.
• Perform the Body Verification Test. Refer to => Non-DTC Based Diagnostics. Body Interior
Test Step 3 - AAT Signal Circuit Shorted to the AAT Return Circuit
• Measure the resistance between the AAT signal circuit and the AAT return circuit in the ambient air temperature sensor harness connector.
Is the resistance more than 100 ohms?
Yes
• Go to Test Step 4 => [ Test
Step 4 - Excessive Resistance in the AAT Signal Circuit ]
No
• Repair the short between the AAT signal circuit and the AAT return circuit.
• Perform the Body Verification Test. Refer to => Non-DTC Based Diagnostics. Body Interior
Test Step 4 - Excessive Resistance in the AAT Signal Circuit
• When checking circuits at the totally integrated power module, be careful not to damage or distort the connector terminals. Improper measurement technique could result in poor pin to terminal contact.
• Measure the resistance of the AAT signal circuit between the ambient air temperature sensor harness connector and the C4 totally integrated power module harness connector.
Is the resistance less than 5.0 ohms?
Yes
• Go to Test Step 5 => [ Test
Step 5 - Ambient Air Temperature Sensor Signal Voltage ]
No
• Repair the excessive resistance in the circuit.
• Perform the Body Verification Test. Refer to => Non-DTC Based Diagnostics. Body Interior
Test Step 5 - Ambient Air Temperature Sensor Signal Voltage
• Turn the ignition OFF.
• Connect the C4 totally integrated power module harness connector.
• Turn the ignition ON.
• With the scan tool, read the ambient air temperature sensor signal voltage.
• The voltage should be approximately 5.0 volts with the connector disconnected.
Is the voltage as described with the connector disconnected?
Yes
• Go to Test Step 6 => [ Test
Step 6 - Ambient Air Temperature Sensor ]
No
• Go to Test Step 7 => [ Test
Step 7 - Totally Integrated Power Module ]
Test Step 6 - Ambient Air Temperature Sensor
• Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the ambient air temperature sensor and the totally integrated power module.
• Look for any chafed, pierced, pinched, or partially broken wires.
• Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the related connectors.
• 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 Body Verification Test. Refer to => Non-DTC Based Diagnostics. Body Interior
No
• Replace the ambient air temperature sensor.
• Perform the Body Verification Test. Refer to => Non-DTC Based Diagnostics. Body Interior
Test Step 7 - Totally Integrated Power Module
• Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the ambient air temperature sensor and the totally integrated power module.
• Look for any chafed, pierced, pinched, or partially broken wires.
• Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the related connectors.
• 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 Body Verification Test. Refer to => Non-DTC Based Diagnostics. Body Interior
No
• Replace the totally integrated power module.
• Perform the Body Verification Test. Refer to => Non-DTC Based Diagnostics. Body Interior