Displays and Gages
DTC B0158
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach
* Diagnostic Procedure Instructions provides an overview of each diagnostic category
DTC Descriptors
DTC B0158 03
- Outside Air Temperature (OAT) Sensor Circuit Voltage Below Threshold
DTC B0158 07
- Outside Air Temperature (OAT) Sensor Circuit Voltage Above Threshold
Diagnostic Fault Information
Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
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 two discreet circuits. 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 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°F (-40°C) in the DIC and an OAT sensor shorted to ground displays +189.5°F (+87.5°C).
Conditions for Running the DTC
The ignition is in ACCESSORY or RUN
* The ignition is ON.
* The system voltage is between 9-16 volts.
Conditions for Setting the DTC
* The HVAC module detects that the outside air temperature is -40°F (-40°C).
* The HVAC module detects that the outside air temperature is 189.5°F (+87.5°C).
Action Taken When the DTC Sets
* 189.5°F (+87.5°C) is displayed in the DIC when the OAT sensor resistance value is less than the lowest OAT sensor resistance threshold.
* -40°F (-40°C) is displayed in the DIC when the OAT sensor resistance value is greater than the highest OAT sensor resistance threshold.
Conditions for Clearing the DTC
* The DTC becomes history when the conditions for setting the DTC are no longer present.
* The history DTC clears after 40 malfunction-free warm-up cycles.
* The HVAC module receives a clear code command from the scan tool.
Circuit/System Verification
The DIC should display approximately 189.5°F (+87.5°C) or -40°F (-40°C).
Circuit/System Testing
1. Ignition OFF disconnect the OAT sensor connector.
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 approximately -40°F (-40°C).
• If the DIC does not display approximately -40°F (-40°C), test the OAT sensor 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:
* AUTO
* A/C OFF
* REAR DEFOGGER
5. 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 approximately 189.5°F (+87.5°C).
• If the DIC does not displays approximately 189.5°F (+87.5°C), 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.
6. If all circuits test normal, test or replace the OAT sensor.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests
* Ambient Air Temperature Sensor Replacement
* Refer to Programming and Relearning Programming and Relearning