Diagnostic Instructions

DTC Descriptors

DTC B0158 02: Outside Air Temperature Sensor Circuit Short to Ground

DTC B0158 05: Outside Air Temperature Sensor Circuit Short to Battery or Open

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Ambient Air Temperature Sensor Signal	B0158 02	B0158 05	B0158 05	--
Low Reference	--	B0173 05, B0158 05, B0163 05, B0509 05	B0173 05, B0158 05, B0163 05, B0509 05	--

Circuit/System Description

The HVAC control module monitors the ambient air temperature sensor with a low reference circuit and 5-volt signal circuit. The HVAC control module monitors the voltage drop across the sensor, which is proportional to temperature. When the ambient air temperatures are cold, the resistance of the sensor is high and the voltage signals are high. When the ambient air temperatures are hot, the resistance of the sensors is low and the voltage signals are low. The HVAC control module converts the voltage value to a temperature value of Celsius and Fahrenheit that will be displayed by the driver information center (DIC).

Conditions for Running the DTC

The ignition is turned ON.

Conditions for Setting the DTC

Action Taken When the DTC Sets

The HVAC control module uses a default air temperature value for further automatic control calculations. The default values are not displayed on the scan tool.

Conditions for Clearing the DTC

Reference Information

Schematic Reference

HVAC Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Ignition ON, observe the scan tool Outside Air Temp. Sensor Raw parameter. The reading should be between -35°C (-39°F) and 85°C (185°F) and change with ambient air temperature changes.

Circuit/System Testing

Important: An instant Outside Air Temperature (OAT) update must be performed by pressing the A/C and Recirc buttons at the same time before and after the system has been serviced to update the filtered ambient air temperature sensor.

1. Ignition OFF, disconnect the harness connector at the ambient air temp sensor.
2. Ignition OFF, test for less than 10 ohms 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, verify the scan tool Outside Air Temp. Sensor Raw parameter is less than -35°C (-39°F).

⇒	If greater than the specified range, test the signal circuit terminal A for a short to ground. If the circuit tests normal, replace the HVAC control module.

4. Install a 3A fused jumper wire between the signal circuit terminal A and the low reference circuit terminal B. Verify the scan tool Outside Air Temp. Sensor Raw parameter is greater than 85°C (185°F).

⇒	If less than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the HVAC control module.

5. If all circuits test normal, test or replace the ambient air temp sensor.

Component Testing

1. Test the ambient air temperature sensor by varying the sensor temperature while monitoring the sensor resistance.
2. Compare the readings with the Sensor Resistance Table and verify that the resistance is within 5 percent of the specification.

⇒	If not within the specified range, replace the sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.