DTC B0249, B0269, B0409, or B0419. Buick Allure 2006

For 1990-2009 cars only

Makes 🢒 Buick 🢒 2006 🢒 Allure 🢒 Restraints 🢒 SIR 🢒 DTC B0249, B0269, B0409, or B0419

Circuit Description

The actuator is an electronic stepper motor. The HVAC control module supplies power and ground to the actuator. The HVAC control module controls the direction of the actuator by changing the polarity of the control circuits. When the actuator reaches its desired position, both circuits are fixed to the same value 0 volts. The HVAC control module determines the door or mode film position by counting pulses (voltage fluctuations) caused by the brush to commutator action generated during normal motor operation. The HVAC control module monitors a voltage drop across an internal resistance to detect the pulses. The HVAC control module converts the pulses to counts with a range of 0-255 counts.

When a calibration or recalibration procedure is performed, the HVAC control module calculates the door or mode film travel range. The HVAC control module commands the actuator in one extreme position then counts pulses starting from 0 counts. The HVAC control module compares the total number of pulses to calibrated limits. If the total pulse count is less than or equal to the maximum calibrated limit and greater than or equal to the minimum calibrated limit, then the calibration is considered successful.

•	Air flow control 3 circuit refers to the mode actuator.

•	Air flow control 7 circuit refers to the recirculation actuator.

•	Temperature control 1 circuit refers to the left air temperature actuator.

•	Temperature control 2 circuit refers to the right air temperature actuator.

DTC Descriptors

This diagnostic procedure supports the following DTCs:

•	DTC B0249 Air Flow Control 3 Circuit Range

•	DTC B0269 Air Flow Control 7 Circuit Range

•	DTC B0409 Temperature Control 1 Circuit Range

•	DTC B0419 Temperature Control 2 Circuit Range

Conditions for Running the DTC

The HVAC control module will run the DTC when either of the following conditions are met.

•	The HVAC control module has completed a calibration/recalibration of the actuator.

•	The HVAC control module commands the actuator to move.

Conditions for Setting the DTC

The HVAC control module will set this DTC if either of the following conditions are true.

•	The actuator fails calibration/recalibration due to an over travel or under travel condition. The HVAC control module does not detect the calibrated number of total pulse counts during a travel range check.

•	The HVAC control module determines that the actual door position does not equal the commanded door position. The HVAC control module commands the door to move but does not see the expected number of pulses between positions.

Action Taken When the DTC Sets

•	The HVAC control module will attempt to make use of whatever range is still available.

•	The HVAC control module will recalibrate the actuator each time the ignition switch is turned ON.

Conditions for Clearing the MIL/DTC

•	The DTC will become history if the HVAC control module no longer detects a failure.

•	The history DTC will clear after 100 fault-free ignition cycles.

•	The DTC can be cleared with a scan tool.

Diagnostic Aids

•	Inspect the appropriate actuator door and actuator for the following conditions:

-	A misaligned actuator--Refer to Mode Actuator Replacement , Temperature Valve Actuator Replacement - Right Side , Temperature Valve Actuator Replacement - Left Side or Recirculation Actuator Replacement .

-	Broken or binding mode actuator film or actuator door

-	Obstruction that prevents the mode film or actuator door from operating within its full range of motion

-	Missing seals to the actuator door

-	Misaligned seals to the actuator door

•	Refer to Testing for Intermittent Conditions and Poor Connections .

Test Description

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

This step verifies that the HVAC control module is able to command the actuator through its full range of motion.

If the actuator does not move at all, the problem is likely to be the drive circuitry within the HVAC control module, the actuator, or the wiring harness. If the actuator does move, but not within its full range of motion, the problem is likely to be a mechanical binding of the actuator door or actuator door linkage.

This step drives the actuator in one direction. The actuator shaft will not move if the actuator door is already in the position you are attempting to drive it to.

This step drives the actuator in the opposite direction.

Step

Action

Values

Yes

Schematic Reference: HVAC Schematics

Connector End View Reference: HVAC Connector End Views

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

Install a scan tool.
Turn the ignition ON, with the engine OFF.
With the scan tool, command the appropriate actuator in both directions.
Observe the appropriate Actual parameter.

Does the scan tool indicate that the value of the appropriate Actual parameter is within 5 counts of the minimum and maximum specified values?

3 Counts

250 Counts

Go to Diagnostic Aids

Go to Step 3

When commanding the actuator in both directions, does the scan tool indicate that the value of the appropriate Actual parameter changes by more than the specified value?

0-3 Counts

Go to Step 7

Go to Step 4

Test the appropriate door control A circuit and the appropriate door control B circuit for an open, high resistance, short to ground or a short to voltage. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 12

Go to Step 5

Turn the ignition OFF.
Disconnect the HVAC control module.
Connect a 10-amp fused jumper wire between the actuator door control A circuit of the appropriate actuator and battery positive voltage.
Connect a 10-amp fused jumper wire between the actuator door control B circuit of the appropriate actuator and a good ground.

Does the actuator shaft rotate?

Go to Step 9

Go to Step 6

Connect a 10-amp fused jumper wire between the actuator door control B circuit of the appropriate actuator and battery positive voltage.
Connect a 10-amp fused jumper wire between the actuator door control A circuit of the appropriate actuator and a good ground.

Does the actuator shaft rotate?

Go to Step 9

Go to Step 7

Inspect the appropriate door and actuator for the following conditions:

•	A misaligned actuator--Refer to Mode Actuator Replacement , Temperature Valve Actuator Replacement - Right Side , Temperature Valve Actuator Replacement - Left Side or Recirculation Actuator Replacement .

•	Broken or binding linkages or actuator door

•	An obstruction that prevents the actuator door from operating within its full range of motion

•	Missing seals to the actuator door

•	Misaligned seals to the actuator door

Did you find and correct the condition?

Go to Step 12

Go to Step 8

Inspect for poor connections at the harness connector of the appropriate actuator. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 12

Go to Step 10

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 .

Did you find and correct the condition?

Go to Step 12

Go to Step 11

Important: Perform the recalibration procedure for the appropriate actuator.

Replace the appropriate actuator. Refer to Mode Actuator Replacement , Temperature Valve Actuator Replacement - Right Side , Temperature Valve Actuator Replacement - Left Side or Recirculation Actuator Replacement .

Did you complete the replacement?

Go to Step 12

Replace the HVAC control module. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 12

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

Does the DTC reset?

Go to Step 3

System OK