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 B0158 05: Outside Air Temperature Sensor Circuit Short to Battery or Open
DTC B0158 06: Outside Air Temperature Sensor Circuit Short to Ground or Open

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Outside Air Temperature Sensor | B0158 06 | B0158 05, B0158 06 | B0158 05 | --
Low Reference | -- | B0158 05, B0158 06 | -- | --

### Circuit/System Description

The body control module (BCM) monitors the outside air temperature sensor to display outside air temperature. The temperature sensor is a 2-wire negative temperature co-efficient thermistor. The BCM applies 5 volts to an internal input resistor that is connected to the signal circuits of the outside air temperature sensor. The BCM provides the ground to the outside air temperature sensor through the low reference circuit. When the outside air temperatures are cold, the resistance of the sensor is high and the voltage signals are high. When the outside air temperatures are hot; the resistance of the sensor is low and the voltage signal is low. The BCM converts the voltage value to a temperature value of Celsius and Fahrenheit that will be displayed by the instrument panel cluster (IPC).

### Conditions for Running the DTC

Ignition ON.

### Conditions for Setting the DTC

• | The BCM detects the sensor signal circuit is less than 0.1 volt.

• | The BCM detects the sensor signal circuit is more than 4.9 volts.

### Action Taken When the DTC Sets

• | The default value of 3°C (38°F) will be substituted for the outside air temperature sensor data by the BCM.

• | 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

#### 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 Ambient Air Temp. Sensor parameter, the reading should be between 0.1 and 4.9 volts and change with temperature.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the outside air temperature sensor.
2. Ignition OFF, test for less than 1.0 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 BCM.

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 or an open/high resistance. If the circuit tests normal, replace the BCM.

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. If the circuit tests normal, replace the BCM.

5. If all circuits test normal, replace the outside air 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.

• | Ambient Air Temperature Gage Sensor Replacement

• | Control Module References for BCM replacement, setup, and programming