B0158

DTC B0158

Diagnostic Instructions
^ Perform the [Diagnostic System Check - Vehicle Diagnostic Information] prior to using this diagnostic procedure. Diagnostic System Check - Vehicle Diagnostic Information
^ Review [Strategy Based Diagnosis] for an overview of the diagnostic approach. Strategy Based Diagnosis
^ [Diagnostic Procedure Instructions - Vehicle Diagnostic Information] provides an overview of each diagnostic category. Diagnostic Procedure Instructions - Vehicle Diagnostic Information

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 a 2-wire negative temperature co-efficient thermistor. The HVAC Control Module applies 5 volts to an internal input resistor that 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 high and the voltage signals are high. When the ambient air temperatures are hot; the resistance of the sensors 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 turned ON.

Conditions for Setting the DTC
^ The HVAC control module detects the sensor signal circuit less than 0.05 volts.
^ The HVAC control module detects the sensor signal circuit more than 4.8 volts.

Action Taken When the DTC Sets
^ The default value of 15 °C (60 °F) will be substituted for the ambient air temperature sensor data by the HVAC control module.
^ The driver information center (DIC) will display the set temperature when ON.

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 50 fault-free ignition cycles.

Circuit/System Verification
Ignition ON, engine OFF, with a scan tool observe the Ambient Air Temperature Sensor parameter through the DIC. The reading should be the ambient temperature. If the display of the DIC for temperature reads dashes, check for a sensor signal circuit fault.

Circuit/System Testing
1. Ignition OFF, disconnect the ambient air temp sensor harness connector at the ambient air temp sensor terminal A.
2. Test for less than 1.0 ohm between the low reference circuit terminal B and ground.
^ If greater than the specified value, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the HVAC control module.

3. Ignition ON, test for 5 volts between the low reference circuit terminal B and the 5-volt reference signal terminal A.
^ If not the specified voltage, test the signal circuit for a short to voltage, short to ground or open/high resistance. If the circuit tests normal, replace the HVAC control module.

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

Repair Instructions
Perform the [Diagnostic Repair Verification - Vehicle Diagnostic Information] after completing the diagnostic procedure. Diagnostic Repair Verification - Vehicle Diagnostic Information
^ [Ambient Air Temperature Sensor Replacement]