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B0268

DTC B0268

CIRCUIT DESCRIPTION
The following DTC is for the recirculation actuator.

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 (9.5 to 12 volts). The HVAC Control Module determines the door 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 travel range. The HVAC Control Module commands the actuator to each extreme position and counts the total number of pulses. 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 7 Circuit refers to the recirculation actuator.

DTC DESCRIPTOR
This diagnostic procedure supports the following DTC.

DTC B0268 Air Flow Control 7 Circuit.




This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description in Vehicle DTC Information.

CONDITIONS FOR RUNNING THE DTC
- The ignition is turned ON.
- The ignition voltage is between 9 to 16 Volts.

CONDITIONS FOR SETTING THE DTC

B0268 2A and 61
Sets after two occurrences of the test fail code setting conditions listed below in the same ignition cycle.

B0268 51 and 04
Sets after one occurrence of the test fail code setting conditions listed below in the same ignition cycle.

B0268 2A, 04, 51 and 61
The following failures occur and set the DTC:
- The HVAC Control Module does not detect any movement of the actuator
- The HVAC Control Module detects a measured recirculation actuator range that exceeds the calibrated value.
- The HVAC Control Module detects a measured recirculation actuator range that is less than the calibrated value.
- The HVAC Control Module detects a calibrate procedure time that exceeds the calibrated value.
- The HVAC Control Module detects the actuator motor as stalled before the recirculation actuator motor reaches the expected stall at the end of the travel. When the drive voltage is reversed the motor is unable to move more than a calibrated amount in the other direction.
- The HVAC Control Module detects the actuator motor as stalled before the recirculation actuator motor reaches the expected stall at the end of the travel. But, when the drive voltage is reversed the motor is able to move more than a calibrated amount in the other direction.

ACTION TAKEN WHEN THE DTC SETS

B0268 2A
The HVAC Control Module will use a default range to retry calibration procedure when ignition is off.

B0268 61
The HVAC Control Module will stop trying to move the recirculation actuator motor during the current ignition cycle.

B0268 04
The HVAC Control Module will retry the command to move the actuator in a certain direction in 5 minute intervals.

B0268 51
The HVAC Control Module will retry calibration when ignition is off.

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 40 fault free ignition cycles.
- The DTC can be cleared with a scan tool.

DIAGNOSTIC AIDS
- Inspect the actuator door and actuator for the following conditions:
- A misaligned recirculation actuator. Refer to Recirculation Actuator Replacement.
- Broken or binding linkages or actuator door
- 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

TEST DESCRIPTION

Steps 1-3:




Steps 4-7:




Steps 8-10:




Steps 11-13:




The numbers below refer to the step numbers on the diagnostic table.
2. This step verifies that the HVAC Control Module is able to command the recirculation actuator through its full range of motion.
3. This step verifies the position of the recirculation actuator.
4. 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.
6. This step drives the actuator in one position. The actuator shaft will not move if the actuator door is already in the position you are attempting to drive it to.
7. This step drives the actuator in the opposite direction.

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