GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2003 🢒 DeVille 🢒 HVAC 🢒 HVAC Systems - Automatic 🢒 DTC B0159, B0164, B0174, B0179, B0510, B0515, or 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 Conditions and Poor Connections in Wiring Systems.

Test Description

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

  1. Tests for the proper operation of the circuit in the high voltage range.

    2.

  2. 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.

Step

Action

Values

Yes

No

Schematic Reference: HVAC Schematics

Connector End View Reference: HVAC Connector End Views

1

Did you perform the HVAC Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - HVAC Systems - Automatic

2
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, observe the appropriate air temperature sensor parameter in the Instrument Panel Module Open/Short Data list.

Does the scan tool indicate that the sensor parameter is within the specified range?

5-250 counts (0.09-4.90 V)

Go to Diagnostic Aids

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Disconnect the appropriate air temperature sensor.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the appropriate sensor parameter in the Instrument Panel Module Open/Short Data list.

Does the scan tool indicate that the sensor parameter is greater than the specified value?

250 counts (4.90 V)

Go to Step 4

Go to Step 5

4

  1. Turn OFF the ignition.
  2. Connect a 3-amp fused jumper wire between the signal circuit of the appropriate air temperature sensor and the low reference circuit of the sensor.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the appropriate sensor parameter in the Instrument Panel Module Open/Short Data list.

Does the scan tool indicate that the sensor parameter is less than the specified value?

5 counts (0.09 V)

Go to Step 8

Go to Step 6

5

Test the signal circuit of the appropriate air temperature sensor for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 12

Go to Step 9

6

Test the signal circuit of the appropriate air temperature sensor for a short to voltage, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 12

Go to Step 7

7

Test the low reference circuit of the appropriate air temperature sensor for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 12

Go to Step 9

8

Inspect for poor connections at the harness connector of the appropriate air temperature sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 12

Go to Step 10

9

Inspect for poor connections at the harness connector of the IPM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 12

Go to Step 11

10

Replace the appropriate air temperature sensor. Refer to Ambient Air Temperature Sensor Replacement , Inside Air Temperature Sensor Replacement , Air Temperature Sensor Replacement - Upper Right Side , Air Temperature Sensor Replacement - Upper Left Side , Air Temperature Sensor Replacement - Lower Left Side or Air Temperature Sensor Replacement - Lower Right Side .

Did you complete the replacement?

--

Go to Step 12

--

11

Important : Perform the recalibration procedure for the IPM.

Replace the IPM. Refer to HVAC Control Module Replacement .

Did you complete the replacement?

--

Go to Step 12

--

12
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK