• | 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. |
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
---|---|---|---|---|
Ambient Air Temperature Sensor Signal | B0158 02 | B0158 05 | B0158 05 | -- |
Low Reference | -- | B0173 05, B0158 05, B0163 05, B0509 05 | B0173 05, B0158 05, B0163 05, B0509 05 | -- |
The HVAC control module monitors the ambient air temperature sensor with a low reference circuit and 5-volt signal circuit. The HVAC control module monitors the voltage drop across the sensor, which is proportional to temperature. 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 HVAC control module converts the voltage value to a temperature value of Celsius and Fahrenheit that will be displayed by the driver information center (DIC).
The ignition is turned ON.
• | The HVAC control module detects the sensor signal circuit is less than -35°C (-39°F). |
• | The HVAC control module detects the sensor signal circuit is more than 85°C (185°F) . |
The HVAC control module uses a default air temperature value for further automatic control calculations. The default values are not displayed on the scan tool.
• | The DTC will become history if the HVAC control module no longer detects a failure. |
• | The history DTC will clear after 100 fault-free ignition cycles. |
Control Module References for scan tool information
Ignition ON, observe the scan tool Outside Air Temp. Sensor Raw parameter. The reading should be between -35°C (-39°F) and 85°C (185°F) and change with ambient air temperature changes.
Important: An instant Outside Air Temperature (OAT) update must be performed by pressing the A/C and Recirc buttons at the same time before and after the system has been serviced to update the filtered ambient air temperature sensor.
⇒ | 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. |
⇒ | 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. |
⇒ | 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. |
⇒ | If not within the specified range, replace the sensor. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for HVAC control module replacement, setup, and programming |