DTC Descriptors

DTC B0158 03: Outside Air Temperature (OAT) Sensor Circuit Voltage Below Threshold

DTC B0158 07: Outside Air Temperature (OAT) Sensor Short to Battery or Open

Diagnostic Fault Information

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Circuit	Short to Ground	Open/High Resistance	Short to Voltage
Outside Air Temperature (OAT) Signal Circuit	B0158 1	B0158 1	B0158 1
Outside Air Temperature (OAT) Ground Reference Circuit	1	B0158 1	1
1. Outside Air Temperature (OAT) Display Inaccurate or Inoperative

Circuit/System Description

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

Conditions for Running the DTC

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 87.5°C (189.5°F) or -40°C (-40°F) .

Circuit/System Testing

1. Ignition OFF disconnect the harness connector at the outside air temperature (OAT) sensor.
2. Ignition OFF, test for less than 1 ohm of resistance between the ground circuit terminal and ground.

⇒	If greater than 1 ohm, test the ground circuit for an open/high resistance.

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

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

4. Ignition ON, install a 3-amp fused jumper wire between the signal circuit and the ground circuit of the OAT sensor. Verify the DIC displays 87.5°C (189.5°F).

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

5. If all circuits test normal, test or replace the OAT sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.