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Makes 🢒 GMC_Truck 🢒 2000 🢒 Sonoma Pickup - 4WD 🢒 HVAC 🢒 HVAC Systems - Automatic 🢒 DTC B0181 Output Air Temp Sensor 2 Circuit High

DTC B0181 Output Air Temp Sensor 2 Circuit High Lower


Object Number: 557007 Size: MF
HVAC Components
ECC Module and Temperature Sensors
Handling ESD Sensitive Parts Notice
ECC Module and Temperature Sensors

Circuit Description

The HVAC control module monitors the lower duct air temperature via a lower air temperature sensor. When the air is cold, the sensor resistance and the signal voltage are high. When the air is warm, the sensor resistance and the signal voltage are low. The HVAC control module requests the A/C compressor clutch engagement and controls the air temperature actuator door position in order to maintain the temperature selected on the HVAC control module.

Conditions for Running the DTC

The ignition is turned ON.

Conditions for Setting the DTC

The HVAC control module detects the fault whenever the temperature is more than 80° C (176° F).

Action Taken When the DTC Sets

The HVAC control module uses a default temperature sensor value of -33° C (-29° F) until the fault is cleared.

Conditions for Clearing the DTC
    • The DTC becomes history when the HVAC control module no longer detects a failure.
    • The history DTC clears after 50 fault-free ignition cycles.
    • The DTC can be cleared with a scan tool.

Diagnostic Aids
    • Visually inspect the sensor connector and harness for corrosion and damage. The resistance value of the sensor must be 47-101,000 ohms. If the resistance is not within the specified value, replace the sensor.
    • Insure lower air temperature sensor is in place and secure. Insure no restrictions or debris around lower air temperature sensor this will give incorrect reading to HVAC control module.
    • If condition is not present refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Test Description

The number(s) below refer to the step number(s) 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

Value(s)

Yes

No

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 Lower Outlet Temperature parameter in the Heating and Air Conditioning Data Display data list.

Does the scan tool indicate that the Lower Outlet Temperature parameter is within the specified range?

-40° to 80° C (-40° to 176° F)

Go to Diagnostic Aids.

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Disconnect the lower air temperature sensor.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the Lower Outlet Temperature parameter.

Does the scan tool indicate that the Lower Outlet Temperature parameter is less than the specified value?

-40° C (-40° F)

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 lower air temperature sensor and the low reference circuit of the lower air temperature sensor.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the Lower Outlet Temperature parameter.

Does the scan tool indicate that the Lower Outlet Temperature parameter is less than the specified value?

80° C (176° F

Go to Step 8

Go to Step 6

5

Test the signal circuit of the lower 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 lower 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 lower 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 lower air temperature sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Special Tools 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 Special Tools in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 12

Go to Step 11

10

Replace the lower air temperature sensor. Refer to Lower Discharge Air Temperature Sensor Replacement .

Did you complete the replacement?

--

Go to Step 12

--

11

Replace the HVAC control module. Refer to Control Assembly 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