P0072

DTC P0071-P0073

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors
DTC P0071
- Ambient Air Temperature Sensor Performance

DTC P0072
- Ambient Air Temperature Sensor Circuit Low Voltage

DTC P0073
- Ambient Air Temperature Sensor Circuit High Voltage

Circuit/System Description

The Vehicle Integration Control Module (VICM) control module supplies the ambient air temperature sensor with a low reference circuit and 5-volt signal circuit. The VICM determines the voltage drop across the sensor, which is proportional to temperature. As the air temperature increases, the sensor resistance decreases. As the air temperature decreases, the sensor resistance increases.

Conditions for Running the DTC

Ignition ON.

Conditions for Setting the DTC

The VICM detects the ambient air temperature sensor signal circuit is less than -36°C (-38°F) or greater than 215°C (419°F) for more than 15 seconds.

Action Taken When the DTC Sets

* The DIC will display SERVICE A/C SYSTEM.
* The system operates using a default value.

Conditions for Clearing the DTC

* The DTC will become history if the VICM no longer detects the condition that set the DTC.
* The history DTC will clear after 100 fault-free ignition cycles.

Reference Information
Schematic Reference

HVAC Schematics HVAC - Automatic
Connector End View Reference

Component Connector End Views Hybrid/EV Battery Pack X1 A4
Description and Operation

Automatic HVAC Description and Operation HVAC - Automatic
Electrical Information Reference

* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs

Scan Tool Reference

Control Module References Control Module References for scan tool information

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the ambient air temperature sensor.
2. Ignition OFF, test for less than 1 ohm between the low reference circuit terminal B and ground.

• If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the HVAC control module.

3. Ignition ON, test for 5 volts between the signal circuit terminal A and the low reference circuit terminal B.

• If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the VICM.
• If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the VICM.

4. If all circuits test normal, test or replace the ambient air temperature sensor.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.

* Ambient Air Temperature Sensor Replacement Ambient Air Temperature Sensor Replacement
* Control Module References Control Module References for VICM replacement, setup, and programming