B0158

DTC B0158

DTC Descriptor

DTC B0158 02
- Outside Air Temperature (OAT) Sensor Short to Ground

DTC B0158 05
- Outside Air Temperature (OAT) Sensor Short to Battery or Open

Diagnostic Fault Information

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview






Circuit/System Description

The outside air temperature sensor is a variable resistor interfaced to the body control module (BCM). The BCM monitors the outside air temperature sensor. The outside air temperature sensor is a 2-wire negative temperature co-efficient thermistor. The BCM applies 5 volts to an internal input resistor connected to the signal circuit 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 temperature is cold, the sensor resistance is high and the signal voltage is high. When the out side air temperature is hot, the sensor resistance is low and the voltage signal is low. The BCM provides the logic for reading the sensor, filtering the data and transmitting this information via the serial data circuit to the driver information center (DIC) for display. The temperature is sent to the instrument panel cluster (IPC) in degrees celsius. The IPC is responsible for displaying the temperature and converting to degrees fahrenheit if necessary. Two serial data signals are ultimately generated. An un-filtered value and a filtered value for use by the DIC display. The BCM also provides the sensor out-of-range detection and compensates for engine temperature by utilizing vehicle speed and engine off time duration. The algorithm for all messages is executed at a rate of once every 1 second.

Conditions for Running the DTC

* The ignition is in ACC or RUN.
* The system voltage is between 9-16 volts.

Conditions for Setting the DTC

The BCM detects that the outside air temperature is 0.4 volt or more than 4.8 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 DIC will display SET TEMPERATURE when ON.

Conditions for Clearing the DTC

* The DTC becomes history when the BCM no longer detects a failure.
* The history DTC clears after 40 malfunction-free ignition cycles.
* The BCM receives a clear code command from the scan tool.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the ambient air temperature.
2. Ignition OFF, test for less than 1 ohm of resistance between the low reference circuit and ground.

• If greater than 1 ohm, test the ground 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 4.7 volts.

• If less than 4.7 volts, test the signal circuit for a short to ground. If the circuit tests normal, replace the BCM.

4. Install a 3-amp fused jumper wire between the signal circuit and ground. Verify the scan tool Ambient Air Temp. Sensor parameter is less than 0.4 volt.

• If greater than 0.4 volt, test the signal circuit for an open/high resistance. If the circuit tests normal replace the BCM.

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

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

* Ambient Air Temperature Sensor Replacement
* Control Module References for BCM replacement, setup, and programming