B0515

DTC B0174, B0179, B0510, or B0515

Circuit Description

Air temperature sensors allow the HVAC control module to monitor the temperature of the discharge air in the HVAC ducts. The module applies 5 volts to internal input resistors that are connected to the signal circuits of the air temperature sensors. The module provides ground to the air temperature sensors through the low reference circuit. The HVAC control module monitors the voltage drops across the air temperature sensors and uses the inputs for automatic control calculations. When the duct air temperatures are cold, the resistances of the sensors are high and the voltage signals are high. When the duct air temperatures are hot, the resistances of the sensors are low and the voltage signals are low. The HVAC control module converts the voltage values to count values where 1 volt is approximately equal to 51 counts.

* Output Air Temperature Sensor 1 refers to the upper left air temperature sensor
* Output Air Temperature Sensor 2 refers to the lower left air temperature sensor
* Output Air Temperature Sensor 3 refers to the upper right air temperature sensor
* Output Air Temperature Sensor 4 refers to the lower right air temperature sensor

DTC Descriptors

This diagnostic procedure supports the following DTCs:

* DTC B0174 Output Air Temperature Sensor 1
* DTC B0179 Output Air Temperature Sensor 2
* DTC B0510 Output Air Temperature Sensor 3
* DTC B0515 Output Air Temperature Sensor 4

Conditions for Running the DTC

* Battery voltage is within 8.7-16.5 volts.
* The ignition is ON.

Conditions for Setting the DTC

The HVAC control module detects the signal circuit is less than 5 counts (0.09 volt) or greater than 250 counts (4.90 volts).

Action Taken When the DTC Sets

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.

Conditions for Clearing the DTC

* The DTC will become history if the HVAC control module no longer detects a fault.
* The history DTC will clear after 100 fault-free ignition cycles.
* The DTC can be cleared with a scan tool.

Test Description

Step 1 - Step 11:

Step 12:

The numbers below refer to the step numbers on the diagnostic table.
2. Verifies that the temperature displayed is not within the calibrated range.
3. Tests for the proper operation of the circuit in the high voltage range.
4. Tests for the proper operation of the circuit in the low voltage range. If the fuse in the jumper opens when you perform this test, the signal circuit is shorted to voltage.