Diagnostic Instructions

DTC Descriptors

DTC B0159: Outside Air Temperature Sensor Circuit Range/Performance

DTC B0164: Passenger Compartment Temperature Sensor 1 Circuit Range/Performance

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Ambient Air Temperature Sensor Signal	B0159	B0159	B0159	--
Inside Air Temperature Sensor	B0164	B0164	B0164	--
Low Reference	--	B0159, B0164	B0159, B0164	--

Circuit/System Description

The ambient air temperature sensor allows the HVAC control module to monitor the temperature of the air surrounding the front of the vehicle. The inside air temperature sensor assembly allows the HVAC control module to monitor the temperature of the air inside the passenger compartment. The module applies 5 volts to internal input resistors that are connected to the signal circuits of the air temperature sensors. The module provides ground to the air temperature sensors through the low reference circuits. The HVAC control module monitors the voltage drops across the air temperature sensors and uses the inputs for automatic control calculations. The HVAC control module also uses the ambient air temperature input to calculate the value of the ambient air temperature display. When the air temperatures are cold, the resistances of the sensors are high and the voltage signals are high. When the air temperatures are hot, the resistances of the sensors are low and the voltage signals are low.

Conditions for Running the DTC

The ignition is turned ON.

Conditions for Setting the DTC

Action Taken When the DTC Sets

The HVAC control module uses a default air temperature value for further automatic control calculations. The default values are not displayed on the scan tool.

Conditions for Clearing the DTC

Reference Information

Schematic Reference

HVAC Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Electrical Information Reference

Scan Tool Reference

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

Important: An instant OAT update must be performed by pressing the A/C and Recirc buttons at the same time before and after the system has been serviced to update the filtered ambient air temperature sensor.

1. Ignition OFF, disconnect the harness connector at the appropriate air temperature sensor.
2. Ignition OFF, test for less than 10 ohms 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 HVAC control module.

3. Ignition ON, verify the scan tool Air Temp Sensor parameter is less than -35°C (-39°F).

⇒	If greater than the specified range, test the 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 signal circuit terminal A and the low reference circuit terminal B. Verify the scan tool Air Temp Sensor 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 air temperature sensor.

Component Testing

1. Test the air temperature sensor by varying the sensor temperature while monitoring the sensor resistance.
2. Compare the readings with the Temperature VS Resistance table Sensor 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 after completing the diagnostic procedure.