HVAC - Automatic
DTC B0160 or B0161
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 B0160
- Outside Air Temperature Sensor Circuit Low
DTC B0161
- Outside Air Temperature Sensor Circuit High
Diagnostic Fault Information
Circuit/System Description
The instrument panel cluster (IPC) monitors the ambient air temperature sensor to display ambient air temperature. The temperature sensor is a 2-wire negative temperature co-efficient thermistor. The IPC applies 5 volts to an internal input resistor that is connected to the signal circuits of the ambient air temperature sensor. The IPC provides the ground to the ambient air temperature sensor through the low reference circuit. The IPC 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 IPC converts the voltage value to a temperature value of Celsius and Fahrenheit that will be displayed by the IPC.
Conditions for Running the DTC
The ignition is turned ON.
Conditions for Setting the DTC
B0160
The IPC detects a short to ground in the sensor signal circuit.
B0161
The IPC detects a short to voltage or an open/high resistance in the sensor signal circuit or the low reference circuit.
Action Taken When the DTC Sets
* The default value of 3°C (38°F) will be substituted for the ambient air temperature sensor data by the IPC.
* The IPC will display the set temperature when ON.
Conditions for Clearing the DTC
* The DTC will become history if the BCM no longer detects a failure.
* The history DTC will clear after 40 fault-free ignition cycles.
Reference Information
Schematic Reference
Instrument Cluster Schematics (Instrument Cluster Schematics)
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 Ambient Air Temp Sensor parameter. The reading should be between 0.1-4.9 volts and change with temperature.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the ambient air temperature sensor.
2. Ignition OFF, test for less than 1.0 ohm of resistance between the 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 IPC.
3. Ignition ON, verify the scan tool Ambient Air Temp Sensor parameter is greater than 4.9 volts.
• If less than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the IPC.
4. Install a 3-amp fused jumper wire between the signal circuit terminal A and the low reference circuit terminal B. Verify the scan tool Ambient Air Temp Sensor parameter is less than 0.1 volt.
• If greater 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 IPC.
5. If all circuits test normal, replace the ambient air temperature sensor.
Component Testing
1. Test the ambient temperature sensor by observing the temperature sensor while also monitoring the sensor resistance.
2. Compare the readings with the temperature versus resistance table, verify that the resistance is within 5 percent of the specification.
• If the resistance versus temperature reading is not within the specified range, replace the ambient air temperature sensor.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
Ambient Air Temperature Sensor Replacement (Service and Repair)