B0520

DTC B0520

CIRCUIT DESCRIPTION
- B0159 Ambient air temperature sensor
- B0164 Inside air temperature assembly
- B0174 Upper left air temperature sensor
- B0510 Upper right air temperature sensor
- B0179 Lower left air temperature sensor
- B0515 Lower right air temperature sensor
- B0520 Auxiliary air temperature sensor

The HVAC control module (IPM) monitors air temperature through air temperature sensors. When the air is cold, the sensor resistance and signal voltage are high. When the air is warm, the sensor resistance and signal voltage are low. The IPM requests A/C compressor clutch engagement and controls the appropriate air temperature actuator door positions in order to maintain the selected air temperature on the IPM. The ambient air temperature is displayed on the HVAC control module (IPM). The inside air temperature assembly contains an electric fan which pulls the air from the passenger compartment to the air temperature sensor.

The IPM monitors the signal circuits of the air temperature sensors for the following conditions:
- Short to ground
- Short to voltage
- An open circuit

CONDITIONS FOR RUNNING THE DTC
The ignition is turned ON.

CONDITIONS FOR SETTING THE DTC
The IPM detects the signal circuit is less than 5 counts (0.09 V) or greater than 250 counts (4.90 V).

ACTION TAKEN WHEN THE DTC SETS
A default value will be used for the sensor data by the IPM. The scan tool displays the default sensor value in the Instrument Panel Module HVAC Sensors data list. The scan tool displays the actual sensor value in the Instrument Panel Module Open/Short data list.

CONDITIONS FOR CLEARING THE DTC
- The DTC will become history if the IPM no longer detects a failure.
- The history DTC will clear after 50 fault free ignition cycles.
- The DTC can be cleared with a scan tool.

DIAGNOSTIC AIDS
If the condition is not present, refer to Testing for Intermittent and Poor Connections in Diagnostic Aids.

TEST DESCRIPTION

Steps 1 - 4:

Steps 5 - 9:

Steps 10 - 12:

The numbers below refer to the step numbers on the diagnostic table.
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.