Volt

DTC P0071-P0073

The Hybrid/EV Powertrain Control Module 2 supplies the ambient air temperature sensor with a low reference circuit and 5 V signal circuit. The Hybrid/EV Powertrain Control Module 2 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.

Vehicle in Service Mode.

The Hybrid/EV Powertrain Control Module 2 detects the ambient air temperature sensor signal circuit is less than -35°C (-39°F) or more than 85°C (185°F) for more than 15 seconds.

Schematic Reference

HVAC Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Automatic HVAC Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

1. Vehicle OFF and all vehicle systems OFF, disconnect the harness connector at the B23 ambient air temperature sensor. It may take up to 2 minutes for all vehicle systems to power down.
2. Test for less than 10 Ω between the low reference circuit terminal B and ground.

⇒	If 10 Ω or greater

2.1.	Vehicle OFF, disconnect the harness connector at the K114A Hybrid/EV powertrain control module 2.

2.2.	Test for less than 2 Ω in the low reference circuit end to end.

⇒	If 2 Ω or greater, repair the open/high resistance in the circuit.

⇒	If less than 2 Ω, replace the K114A Hybrid/EV powertrain control module 2.

⇓	If less than 10 Ω

3. Vehicle in Service Mode.
4. Verify the scan tool Ambient Air Temperature Sensor parameter is less than -35°F.

⇒	If -35°F or greater

4.1.	Vehicle OFF, disconnect the harness connector at the K114A Hybrid/EV powertrain control module 2.

4.2.	Test for infinite resistance between the signal circuit terminal A and ground.

⇒	If less than infinite resistance, repair the short to ground on the circuit.

⇒	If infinite resistance, replace the K114A Hybrid/EV powertrain control module 2.

⇓	If less than -35°F

5. Install a 3 A fused jumper wire between the signal circuit terminal A and the low reference circuit terminal B.
6. Verify the scan tool Ambient Air Temperature Sensor parameter is greater than 240°F.

⇒	If 240°F or less

6.1.	Vehicle OFF, disconnect the harness connector at the K114A Hybrid/EV powertrain control module 2, vehicle in Service Mode.

6.2.	Test for less than 1 V between the signal circuit and ground.

⇒	If 1 V or greater, repair the short to voltage on the circuit.

⇓	If less than 1 V

6.3.	Vehicle OFF

6.4.	Test for less than 2 Ω in the signal circuit end to end.

⇒	If 2 Ω or greater, repair the open/high resistance in the circuit.

⇒	If less than 2 Ω, replace the K114A Hybrid/EV powertrain control module 2.

⇓	If greater than 240°F

7. Test or replace the B23 ambient air temperature sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.