GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2000 🢒 DeVille 🢒 HVAC 🢒 HVAC Systems - Automatic 🢒 DTC B0159 Outside Air Temperature Sensor Circuit Range/Performance

Circuit Description

The HVAC control module (IPM) monitors the ambient air temperature through an ambient air temperature sensor. 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 HVAC control module displays the ambient air temperature.

Conditions for Running the DTC

The ignition is turned ON.

Conditions for Setting the DTC

The HVAC control module 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 HVAC control module. The temperature displayed on the scan tool in the Instrument Panel Module HVAC Sensors data list will be the default value. The actual sensor reading will be displayed on the scan tool in the Instrument Panel Module Open/Short Data list.
    • The HVAC control module will display " - -" for ambient air temperature.

Conditions for Clearing the DTC
    • The DTC will become history if the HVAC control module 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 condition 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 Blower Control Schematics , HVAC Compressor Control Schematics , and HVAC Air Delivery/Temperature Control Schematics

1

Did you perform the HVAC Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check

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

Does the scan tool indicate that the Outside Air Temp 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 ambient air temperature sensor.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the Outside Air Temp parameter.

Does the scan tool indicate that the Outside Air Temp 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 temperature sensor input circuit of the ambient air temperature sensor and the sensor return circuit of the ambient air temperature sensor.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the Outside Air Temp parameter.

Does the scan tool indicate that the Outside Air Temp parameter is less than the specified value?

5 Counts (0.09 V)

Go to Step 8

Go to Step 6

5

Test the temperature sensor input circuit of the ambient 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 temperature sensor input circuit of the ambient 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 sensor return circuit of the ambient 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 ambient 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 HVAC control module. 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 ambient air temperature sensor. Refer to Ambient Temperature Sensor Replacement .

Did you complete the replacement?

--

Go to Step 12

--

11

Important: Perform the recalibration procedure Instrument Panel Module Recalibration for the HVAC control module.

Replace the HVAC control module. Refer to HVAC Module Assembly Replacement in Heating, Ventilation, and Air Conditioning.

Did you complete the replacement?

--

Go to Step 12

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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