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: Ambient Air Temperature Sensor Circuit short to battery or openDTC B0158 06: Ambient Air Temperature Sensor Circuit short to ground or open
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Ambient Air Temperature Sensor Circuit | B0158 06 | B0158 06 B0158 05 | B0158 05 | -- |
Low Reference Circuit | -- | B0158 06 B0158 05 | -- | -- |
Circuit/System Description
The body control module (BCM) monitors the ambient air temperature sensor to display ambient 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 ambient air temperature sensor. The BCM provides the ground to the ambient air temperature sensor through the low reference circuit. The BCM 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 BCM converts the voltage value to a temperature value of Celsius and Fahrenheit that will be displayed by the instrument cluster display (IPC).
Conditions for Running the DTC
The ignition is turned 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 ambient air temperature sensor data by the BCM. |
| • | The instrument cluster display (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
Connector End View Reference
Electrical Information Reference
Scan Tool Reference
Circuit/System Verification
Ignition ON, Engine OFF, observe the scan tool Ambient Air Temperature Sensor voltage parameter in the BCM data list. The reading should be between 0.1 and 4.9 Volts and change with temperature.
Circuit/System Testing
- Ignition OFF, disconnect the ambient air temp sensor harness connector at the ambient air temp sensor.
- Ignition OFF, test for less than 1.0 ohm of resistance between the low reference circuit terminal and ground.
- Ignition ON, verify the scan tool Ambient Air Temp Sensor voltage parameter is greater than 4.9 volts.
- Install a 3-amp fused jumper wire between the signal circuit terminal and the low reference circuit terminal. Verify the scan tool Ambient Air Temp Sensor voltage parameter in the BCM data list is less than 0.1 volt.
- If all circuits test normal, replace the Ambient Air Temp Sensor.
| ⇒ | If greater than 1.0 ohm, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the BCM. |
| ⇒ | If less than 0.1 volt test the signal circuit for a short to ground. If the circuit tests normal, replace the BCM. |
| ⇒ | If greater than 0.1 volt, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM. |
Component Testing
A thermometer is the proper tool to use when checking the actual ambient temperature line. Ambient temperature should not be taken from a radio station, or a sign displaying temperature.
- Test the ambient temperature sensor by observing the temperature sensor while also monitoring the sensor resistance.
- Compare the readings with the temperature versus resistance table refer to Sensor Resistance Table verify that the resistance is within 5 percent of the specification.
| ⇒ | If the resistance versus temperature reading is not within the 5 percent, replace the ambient air temperature sensor. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for BCM replacement, setup, and programming |
