Diagnostic Instructions

DTC Descriptors

DTC B0158 04: Outside Air Temperature (OAT) Sensor Open

DTC B0158 05: Outside Air Temperature (OAT) Sensor Short to Battery or Open

DTC B0158 06: Outside Air Temperature (OAT) Sensor Short to Ground or Open

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage
Outside Air Temperature (OAT) Signal Circuit	B0158 06	B0158 04	B0158 05
Outside Air Temperature (OAT) Ground Reference Circuit	--	B0158 04	--

Circuit/System Description

The HVAC module monitors the signal circuit of the ambient air temperature sensor. The ambient air temperature sensor is a thermistor which varies in resistance as the temperature changes. When the resistance of the ambient air temperature sensor increases, the ambient air temperature is cold. When the resistance of the ambient air temperature sensor decreases, the ambient air temperature is high. The HVAC module interfaces with the ambient air temperature sensor via the signal circuit. The HVAC module applies 5 volts to an internal input resistor that is connected to the signal circuit of the ambient air temperature sensor . The HVAC module uses the ambient air temperature resistance and voltage for automatic control calculations and conversion to temperature values. The HVAC module sends the ambient air temperature value to the instrument panel cluster (IPC) via the serial data circuit for display in the driver information center (DIC). If the ambient air temperature sensor is opened or shorted, the temperature display is either a cold or hot extreme. An open ambient air temperature sensor will display -40°F (-40°C) in the DIC and an ambient air temperature sensor shorted to ground displays +189.5°F (+87.5°C).

Conditions for Running the DTC

The ignition is in ACCESSORY or RUN.

Conditions for Setting the DTC

Action Taken When the DTC Sets

Conditions for Clearing the DTC

Reference Information

Schematic Reference

Connector End View Reference

Electrical Information Reference

Scan Tool Reference

Circuit/System Verification

The DIC should display +189.5°F (+87.5°C) or -40°F (-40°C) .

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 of resistance between the ground circuit terminal B and ground.

⇒	If greater than the specified range, test the ground circuit for an open/high resistance.

3. Ignition ON, verify the DIC displays approximately -40°F (-40°C).

⇒	If the DIC does not display approximately -40°F (-40°C), test the signal circuit for a short to ground. If the circuit tests normal, replace the HVAC module.

4. Ignition ON, perform an outside air temperature Instant Update to by pass filtering by simultaneously pressing the following switches on the HVAC control module:

•	LEFT TEMPERATURE UP

•	PASS ENABLE

•	REAR DEFOG ENABLE

5. Ignition ON, install a 3-amp fused jumper wire between the signal circuit terminal A and ground. Verify the DIC displays approximately 189.5°F (87.5°C).

⇒	If the DIC does not display approximately 189.5°F (87.5°C), test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the HVAC module.

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

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.