B0168
DTC B0158 or B0168
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category
DTC Descriptors
DTC B0158 03
- Outside Air Temperature Sensor Circuit Voltage Below Threshold
DTC B0158 07
- Outside Air Temperature Sensor Circuit Voltage Above Threshold
DTC B0168 03
- Passenger Compartment Temperature Sensor Voltage Below Threshold
DTC B0168 07
- Passenger Compartment Temperature Sensor Voltage Above Threshold
Diagnostic Fault Information
Circuit Description
The HVAC control module monitors the air temperature sensors with a low reference circuit and 5-volt signal circuit. The HVAC control module monitors the voltage drop across the sensor. 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.
Conditions for Running the DTC
The ignition is ON.
Conditions for Setting the DTC
* The HVAC control module detects the sensor signal circuit is less than -35°C (-39°F).
* The HVAC control module detects the sensor signal circuit is greater than 85°C (185°F).
Action Taken When the DTC Sets
B0158
* The DIC display will display "-" for outside air temperature.
* The system operates using a default value.
* A warning will display on the Driver Information Center (DIC) "Service Air Conditioning System ".
B0168
* The system operates using a default value.
* A warning will display on the Driver Information Center (DIC) "Service Air Conditioning System ".
Conditions for Clearing the DTC
* The condition for setting the DTC is no longer present.
* The HVAC control module automatically clears the history DTC when a current DTC is not detected in 50 fault-free ignition cycles.
* The DTC can be cleared using a scan tool.
Reference Information
Schematic Reference
HVAC Schematics Electrical Diagrams
Connector End View Reference
Component Connector End Views Fuel Pump and Level Sensor Assembly
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
Scan Tool Reference
Control Module References Control Module References for scan tool information
Circuit/System Verification
Ignition ON, observe the appropriate scan tool Air Temp Sensor parameter. The reading should be between -35°C (-39°F) and 85°C (185°F) and change with air temperature changes.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the appropriate air temperature sensor.
2. Ignition OFF, test for less than 10 ohms between the following low reference circuit terminal and ground.
* Outside air temperature sensor terminal A
* Inside air temperature sensor terminal B
• 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, test for 5 volts between the low reference circuit terminal and the 5-volt reference signal circuit terminal.
• 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.
* Outside air temperature sensor terminal B
* Inside air temperature sensor terminal A
4. If all circuits test normal, test or replace the air temperature sensor.
Component Testing
Ignition OFF, remove the appropriate temperature sensor and perform a resistance test across the sensor terminals. Verify that the resistance readings correspond with those in the sensor resistance tables. If outside of the specified range, replace the appropriate sensor.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Ambient Air Temperature Sensor Replacement (LHD) Service and Repair
* Inside Air Temperature Sensor Replacement (LHD) Service and Repair
* Control Module References Control Module References for HVAC control module replacement, setup, and programming