HVAC - Automatic
DTC B0158
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.
DTC Descriptors
DTC B0158 13
- Outside Air Temperature Sensor Voltage Low
DTC B0158 14
- Outside Air Temperature Sensor Voltage High
Diagnostic Fault Information
Circuit/System Description
The HVAC control module monitors the ambient air temperature sensor to display ambient air temperature. The temperature sensor is a 2-wire negative temperature co-efficient thermistor. The HVAC control module applies 5 volts to an internal input resistor that is connected to the signal circuits of the ambient air temperature sensor. The HVAC control module provides the ground to the ambient air temperature sensor through the low reference circuit. The HVAC control module monitors the voltage drop across the ambient air temperature sensor and uses the input for automatic control calculations. 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
Ignition ON.
Conditions for Setting the DTC
* The HVAC control module detects the sensor signal circuit is less than 0.05 volts.
* The HVAC control module detects the sensor signal circuit is greater than 4.9 volts.
Action Taken When the DTC Sets
* The default value of 85°C (185°F) will be substituted for the ambient air temperature sensor data by the HVAC control module.
* The DIC will display - -.
Conditions for Clearing the DTC
* The DTC will become history if the HVAC control module no longer detects a failure.
* The history DTC will clear after 100 fault-free ignition cycles.
Reference Information
Schematic Reference
HVAC Schematics (HVAC - Automatic)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
* Air Temperature Description and Operation (Air Temperature Description and Operation)
* Air Delivery Description and Operation (Air Delivery Description and Operation)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Circuit/System Verification
Ignition ON, observe the scan tool Outside Air Temp. Raw parameter. The reading should be between -35 and +85°C (-39 and +185°F) and change with air temperature changes.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the ambient air temperature sensor.
2. Ignition OFF, test for less than 10 ohms between the following 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. Raw parameter is less than -35°C (-39°F).
• If greater than the specified range, test the following 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 following signal circuit terminal A and the low reference circuit terminal B. Verify the scan tool Outside Air Temp. 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 temperature sensor.
Component Testing
1. A thermometer can be used to test the sensor off the vehicle in warn and or cold water. Sensor Resistance Table (HVAC - Automatic) for this test.
2. Test the ambient air temperature sensor by varying the sensor temperature while monitoring the sensor resistance.
3. Compare the readings with the Temperature VS 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 (Verification Tests) after completing the diagnostic procedure.
* Ambient Air Temperature Sensor Replacement (Service and Repair)
* Control Module References (Programming and Relearning) for HVAC control module replacement, setup, and programming