Diagnostic Instructions

DTC Descriptors

DTC B0158 02: Outside Air Temperature Sensor Circuit Short to Ground

DTC B0158 05: Outside Air Temperature Sensor Circuit Short to Battery or Open

DTC B0163 02: Passenger Compartment Temp Sensor 1 Circuit Short to Ground

DTC B0163 05: Passenger Compartment Temp Sensor 1 Circuit Short to Battery or Open

DTC B0168 02: Passenger Compartment Temp Sensor 2 Circuit Short to Ground

DTC B0168 05: Passenger Compartment Temp Sensor 2 Circuit Short to Battery or Open

DTC B0173 02: Output Air Temperature Sensor 1 Circuit Short to Ground

DTC B0173 05: Output Air Temperature Sensor 1 Circuit Short to Battery or Open

DTC B0178 02: Output Air Temperature Sensor 2 Circuit Short to Ground

DTC B0178 05: Output Air Temperature Sensor 2 Circuit Short to Battery or Open

DTC B0509 02: Output Air Temperature Sensor 3 Circuit Short to Ground

DTC B0509 05: Output Air Temperature Sensor 3 Circuit Short to Battery or Open

DTC B0514 02: Output Air Temperature Sensor 4 Circuit Short to Ground

DTC B0514 05: Output Air Temperature Sensor 4 Circuit Short to Battery or Open

DTC B3578 02: Output Air Temperature Sensor 6 Circuit Short to Ground

DTC B3578 05: Output Air Temperature Sensor 6 Circuit Short to Battery or Open

DTC B3583 02: Output Air Temperature Sensor 7 Circuit Short to Ground

DTC B3583 05: Output Air Temperature Sensor 7 Circuit Short to Battery or Open

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Inside Air Temperature Sensor Signal	B0163 02	B0163 05	B0163 05	1
Ambient Air Temperature Sensor Signal	B0158 02	B0158 05	B0158 05	1
Upper Left Air Temperature Sensor Signal	B0173 02	B0173 05	B0173 05	1
Upper Right Air Temperature Sensor Signal	B0509 02	B0509 05	B0509 05	1
Lower Left Air Temperature Sensor Signal	B0178 02	B0178 05	B0178 05	1
Lower Right Air Temperature Sensor Signal	B0514 02	B0514 05	B0514 05	1
Lower Auxiliary Air Temperature Sensor Signal	B3583 02	B3583 05	B3583 05	1
Upper Auxiliary Air Temperature Sensor Signal	B3578 02	B3578 05	B3578 05	1
Auxiliary Inside Air Temperature Sensor Signal	B0168 02	B0168 05	B0168 05	1
Right Sunload Sensor Signal	B0188 02	B0188 05	B0188 05	1
Left Sunload Sensor Signal	B0183 02	B0183 05	B0183 05	1
Low Reference	--	B0173 05, B0158 05, B0163 05, B0509 05, B0178 05, B0514 05, B3933 05	B0173 05, B0158 05, B0163 05, B0509 05, B0178 05, B0514 05, B3933 05	1
Sunload Sensor Ground	B0183 02, B0188 02	B0183 05, B0188 05	B0183 05, B0188 05	1
1. Air Temperature Malfunction

Circuit/System Description

Air Temperature Sensors

The air temperature sensors are a 2-wire negative temperature co-efficient thermistor. The vehicle uses the following air temperature sensors:

A signal and low reference circuit enables the sensor to operate. As the air temperature surrounding the sensor increases, the sensor resistance decreases. The sensor signal voltage decreases as the resistance decreases. The sensor operates within a temperature range between -40 to +101°C (-40 to +215°F). The sensor signal varies between 0-5 volts. The HVAC control module converts the signal to a range between 0-255 counts. As the air temperature increases the count value will decrease. If the HVAC control module or auxiliary HVAC control module detects a malfunctioning sensor, then the control module software will use a defaulted air temperature value. The default value for the ambient and inside air temperature sensors will be displayed on the scan tool. The default value for the duct air temperature sensors will not be displayed on the scan tool. The scan tool parameter for the duct air temperature sensors are the actual state of the signal circuit. The default action ensures that the HVAC system can adjust the inside air temperature near the desired temperature until the condition is corrected.

Diagnostic Aids

Ambient Air Temperature Display Update

Condition	Display
Using Scan Tool Special Function	Updates temperature display instantly
When the HVAC module MODE, FRONT DEFROST, and REAR DEFROST buttons are pressed simultaneously.	Updates temperature display instantly
At start up with the engine off less than 2 hours	Displays last stored temperature unless temperature has decreased. The outside air temperature reading is always instantly updated if ambient air temperature has decreased.
At start up with the engine off more than 2 hours	Displays actual outside temperature
Vehicle speed above 32 km/h (20 mph) for a minimum of 80 seconds	Updates temperature display at a slow filtered rate
Vehicle speed above 72 km/h (45 mph)	Displays actual outside temperature
Sensor ambient temperature reading is less than the last displayed value	Displays actual outside temperature
When the ambient air decreases	Updates temperature display rapidly

Conditions for Running the DTC

Ignition ON.

Conditions for Setting the DTC

The HVAC control module detects the temperature sensor signal circuit is less than -36°C (-38°F) or greater than 215°C (419°F) for greater than 15 seconds.

Action Taken When the DTC Sets

The system operates using a default value.

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

1. Measure actual outside air temperature using a thermometer. Compare this value to the scan tool Outside Air Temp. Raw parameter. The measured temperature should be within 5 degrees of parameter.

⇒	If not within the specified range, refer to Ambient / Inside Air Temperature Sensor Circuit Malfunction.

2. Measure actual inside air temperature using a thermometer. Compare this value to the scan tool Inside Air Temp. Sensor parameter and Aux. Inside Air Temp. parameter. The measured temperature should be within 5 degrees of parameter.

⇒	If not within the specified range, refer to Ambient / Inside Air Temperature Sensor Circuit Malfunction.

3. Measure actual temperature using a thermometer at each of the duct temperature sensors. Compare this value to the appropriate scan tool Duct Actual parameter. The measured temperature should be within 5 degrees of appropriate Duct Actual parameter.

⇒	If not within the specified range, refer to Duct Temperature Sensor Circuit Malfunction.

Circuit/System Testing

Ambient / Inside Air Temperature Sensor Circuit Malfunction

1. Ignition OFF, disconnect the harness connector at the appropriate temperature sensor.
2. Test for less than 1 ohm 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 appropriate scan tool Temp Sensor parameter is greater than 4.9 volts or 250 counts.

⇒	If less 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 3-amp fused jumper wire between the signal circuit terminal A and the low reference circuit terminal B. Verify the scan tool Temp Sensor parameter is less than 0.1 volt or 5 counts.

⇒	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 HVAC control module.

5. If all circuits test normal, test or replace the appropriate temperature sensor.

Duct Temperature Sensor Circuit Malfunction

1. Ignition OFF, disconnect the harness connector at the appropriate temperature sensor.
2. Test for less than 1.0 ohm between the low reference circuit terminal 2 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 appropriate Duct Temp Sensor Actual parameter is greater than 4.9 volts or 250 counts.

⇒	If less than the specified range, test the signal circuit terminal 1 for a short to ground. If the circuit tests normal, replace the HVAC control module.

4. Install a 3-amp fused jumper wire between the signal circuit terminal 1 and the low reference circuit terminal 2. Verify the scan tool Duct Temp Sensor Actual parameter is less than 0.1 volt or 5 counts.

⇒	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 HVAC control module.

5. If all circuits test normal, test or replace the appropriate 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 for this test.
2. Test the evaporator 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 after completing the diagnostic procedure.