For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### DTC Descriptors

DTC B0163 02: Passenger Compartment Temperature Sensor Circuit Short to Ground
DTC B0163 05: Passenger Compartment Temperature Sensor 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 | --
Low Reference | -- | B0173 05, B0158 05, B0163 05, B0509 05 | B0173 05, B0158 05, B0163 05, B0509 05 | --

### Circuit/System Description

The HVAC control module supplies the inside air temperature sensor with a low reference circuit and 5-volt signal circuit. The HVAC control module determines the voltage drop across the sensor, which is proportional to temperature. As the air temperature increases, the sensor resistance decreases and the voltage signal decreases. As the air temperature decreases, the sensor resistance increases and the voltage signal increases.

Passenger compartment temperature sensor refers to the inside air temperature sensor.

### Conditions for Running the DTC

The ignition is turned ON.

### Conditions for Setting the DTC

The HVAC control module detects the inside air 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

• | The DTC will become history if the HVAC control module no longer detects the condition that set the DTC.

• | The history DTC will clear after 100 fault-free ignition cycles.

### Reference Information

#### Schematic Reference

HVAC Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

• | Air Temperature Description and Operation

• | Air Delivery Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

Ignition ON, observe the scan tool Inside Air Temperature Sensor parameter. The reading should be between -35°C (-39°F) and 98°C (208°F) and change with inside air temperature changes.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the inside air temp 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 inside 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 Inside Air Temp. Sensor 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 inside air temp sensor.

### Component Testing

1. Test the inside air temperature sensor by varying the sensor temperature while monitoring the sensor resistance.
2. Compare the readings with the 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.

• | Inside Air Temperature Sensor Aspirator Replacement

• | Control Module References for HVAC control module replacement, setup and programming