Buick Regal: DTC B0223, B022A, B0233, B023A, B0408, or B0418

Diagnostic Instructions

• Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
• Review Strategy Based Diagnosis for an overview of the diagnostic approach.
• Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC B0223 01

Recirculate Position Command 1 Circuit Short to Battery

DTC B0223 06

Recirculate Position Command 1 Circuit Low Voltage/Open

DTC B022A 01

Recirculate Position Command 2 Circuit Short to Battery

DTC B022A 06

Recirculate Position Command 2 Circuit Low Voltage/Open

DTC B0233 01

Air Flow Control Circuit Short to Battery

DTC B0233 06

Air Flow Control Circuit Low Voltage/Open

DTC B023A 02

HVAC Actuators Supply Voltage Short to Ground

DTC B0408 01

Main Temperature Control Circuit Short to Battery

DTC B0408 06

Main Temperature Control Circuit Low Voltage/Open

DTC B0418 01

Right Temperature Control Circuit Short to Battery

DTC B0418 06

Right Temperature Control Circuit Low Voltage/Open

Diagnostic Fault Information

Circuit/System Description

Stepper motors are used for temperature regulation, air distribution control and recirculation door control.

With the switches and dials on the HVAC controls, air temperature door position, mode door position and recirculation door position can be selected. The selected values are passed to the HVAC control module via serial data. The HVAC control module supplies a 12 V control voltage to the stepper motors and energizes the 4 stepper motor coils with a pulsed ground signal. The stepper motors move the appropriate doors into the calculated positions, in order to reach the desired positions.

Conditions for Running the DTC

• Ignition ON.
• The HVAC control module is ON.

Conditions for Setting the DTC

B023A 02

The stepper motors supply output is shorted to ground.

B0223 01, B022A 01, B0233 01, B023A 01, B0408 01 or B0418 01

At least one control circuits of the appropriate stepper motor is shorted to voltage when motor starts moving. Faults are not detected when motor is already running or target position is already reached.

B0223 06, B022A 06, B0233 06, B0233 06, B0408 06 or B0418 06

At least one control circuits of the appropriate stepper motor is shorted to ground or open when motor starts moving. Faults are not detected when motor is already running or target position is already reached.

Action Taken When the DTC Sets

B023A

• The affected output will be switched off for hardware protection.
• All stepper motors are deactivated.

B0223, B022A, B0233, B0408 or B0418,

• The affected output will be switched off for hardware protection.
• The affected stepper motor is deactivated.

Conditions for Clearing the DTC

The condition for setting the DTC is no longer present.

Reference Information

Schematic Reference

HVAC Wiring Schematics

Connector End View Reference

Component Connector End View Index

Description and Operation

Automatic HVAC Description and Operation

Electrical Information Reference

• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information.

Circuit/System Verification

1. Perform the Actuator Recalibration procedure.

2. Verify the concern or DTC has been corrected.

• If the concern or DTC has not been corrected

1. Verify DTC B023A is not set.
   • If DTC B023A is set

   Refer to Circuit/System Testing - DTC B023A.

   • If DTC B023A is not set

   Refer to Circuit/System Testing - DTC B0223, B022A, B0233, B0408 or B0418.

• Go to next step: If the concern or DTC has been corrected

3. All OK.

Circuit/System Testing

(DTC B023A)

1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the components listed below. It may take up to 2 min for all vehicle systems to power down.

• M4 Air Inlet Door Actuator
• M37 Mode Door Actuator
• M46 Air Recirculation Door Actuator
• M6L Air Temperature Door Actuator - Left
• M6R Air Temperature Door Actuator - Right

2. Disconnect the X3 and X4 harness connectors at the K33 HVAC Control Module.

3. Test for infinite resistance between the K33 HVAC Control Module 12 V reference circuit terminal 15 X3 and ground.

• If less than infinite resistance

Repair the short to ground on the circuit.

• Go to next step: If infinite resistance

4. Ignition ON.

5. Test for less than 1 V between the K33 HVAC Control Module 12 V reference circuit terminal 15 X3 and ground.

• If 1 V or greater

Repair the short to voltage on the circuit.

• Go to next step: If less than 1 V

6. Connect the X3 and X4 harness connectors at the K33 HVAC Control Module, ignition ON.

7. Clear all DTCs.

8. Verify DTC B023A is not set.

• If the DTC is set.

Replace the K33 HVAC Control Module.

• Go to next step: If the DTC is not set.

9. Verify DTC B023A does not set after connecting each of the components listed below one at a time and operating them through their full range.

• M4 Air Inlet Door Actuator
• M37 Mode Door Actuator
• M46 Air Recirculation Door Actuator
• M6L Air Temperature Door Actuator - Left
• M6R Air Temperature Door Actuator - Right
• If the DTC sets

Replace the component that was connected immediately before the DTC set.

• Go to next step: If the DTC does not set

10. All OK.

(DTC B0223, B022A, B0233, B0408 or B0418)

1. Ignition OFF, disconnect the harness connector at the appropriate door actuator, ignition ON.

2. Verify a test lamp flashes when connected between the 12 V reference circuit terminal 2 and ground.

• If the test lamp does not flash

1. Ignition OFF, remove the test lamp and disconnect the harness connector at the K33 HVAC Control Module.
2. Test for less than 2 Ω in the 12 V control circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.
   • If less than 2 Ω, replace the K33 HVAC Control Module.

• Go to next step: If the test lamp flashes

3. Connect a test lamp between each control circuit listed below and B+.

• Control Circuit - terminal 1
• Control Circuit - terminal 3
• Control Circuit - terminal 4
• Control Circuit - terminal 6

4. Command the appropriate door actuator in both directions.

5. Verify the test lamp turns ON and then OFF during at least one of the directional commands.

• If the test lamp is always ON

1. Ignition OFF, remove the test lamp and disconnect the harness connector at the K33 HVAC Control Module.
2. Test for infinite resistance between the control circuit and ground.
   • If less than infinite resistance, repair the short to ground on the circuit.
   • If infinite resistance, replace the K33 HVAC Control Module.

• If the test lamp is always OFF

1. Ignition OFF, remove the test lamp and disconnect the harness connector at the K33 HVAC Control Module, ignition ON.
2. Test for less than 1 V between the control circuit and ground.
   • If 1 V or greater, repair the short to voltage on the circuit.
   • Go to next step: If less than 1 V
3. Ignition OFF
4. Test for less than 2 Ω in the control circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance is the circuit.
   • If less than 2 Ω, replace the K33 HVAC Control Module.

• Go to next step: If the test lamp turns ON and then OFF

6. Replace the door actuator.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

• HVAC Component Replacement Reference
• Control Module References for HVAC control module replacement, programming and setup

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