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B0408




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

Diagnostic Instructions

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

DTC Descriptors
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 flap control.

With the appropriate switches at the Radio/HVAC control, the desired air temperature flap position, air distribution flap position and recirculation flap position can be put in. The selected values are passed to the HVAC control module via the LIN-Bus. The HVAC control module supplies a 12 V reference voltage to the stepper motors and energizes the 4 stepper motor coils with a pulsed ground signal. The stepper motors put the appropriate flap into the calculated position, in order to reach the put in temperature/position.

* DTC B0223 is for the recirculation door motor.
* DTC B022A is for the air inlet actuator.
* DTC B0233 is for the mode door actuator.
* DTC B0408 is for the air temperature door actuator - left.
* DTC B0418 is for the air temperature door actuator - right.

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, B0408 01 or B0418 01

At least one control output (of four possible outputs) 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, B0408 06 or B0418 06

At least one control output (of four possible outputs) 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 02
* 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 Schematics (Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
Description and Operation

Automatic HVAC Description and Operation (Description and Operation)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information

Circuit/System Verification

1. Verify that DTC B023A 02 is not present.

• If DTC is present, refer to Actuator Power Supply Malfunction.

2. Verify that DTC B0223, B022A, B0233, B0408 or B0418 is not set.

• If DTC is present, refer to Actuator Malfunction.

Circuit/System Testing

Actuator Power Supply Malfunction
1. Ignition OFF, disconnect the X3 harness connector at the K33 HVAC Control Module.
2. Test for infinite resistance between the 12 V reference voltage circuit terminal 15 X3 and ground.

• If less than the specified value, test the reference voltage circuit for a short to ground.

3. If all circuits test normal, test or replace the K33 HVAC Control Module.

Actuator Malfunction
1. Ignition OFF, disconnect the X3 and X4 harness connector at the K33 HVAC Control Module.
2. Ignition ON, verify that a test lamp does not illuminate between each control circuit terminal of the appropriate actuator and ground.

• If the test lamp illuminates, test each control circuit for a short to voltage.

3. Ignition OFF, test for infinite resistance between each control circuit terminal of the appropriate actuator and ground.

• If less than the specified value, test each control circuit for a short to ground.

4. Test for 80-120 ohm between the 12 V reference voltage circuit terminal 15 X3 and each control circuit terminal of the appropriate actuator.

• If less than the specified range, test for the 12 V reference voltage circuit and the control circuit for a short circuit. If the circuits test normal, replace the appropriate actuator.
• If greater than the specified range, test the 12 V reference voltage circuit and the control circuit for an open/high resistance. If the circuits test normal, replace the appropriate actuator.

5. If all circuits test normal, replace the K33 HVAC Control Module.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Temperature Valve Actuator Replacement - Left Side (Left Hand Drive) (Temperature Valve Actuator Replacement - Left Side (Left Hand Drive))
* Temperature Valve Actuator Replacement - Right Side (Temperature Valve Actuator Replacement - Right Side)
* Mode Control Cam Actuator Replacement (Left Hand Drive) (Mode Control Cam Actuator Replacement (Left Hand Drive))
* Inside Air Valve Actuator Replacement (Service and Repair)
* Control Module References (Programming and Relearning) for HVAC control module replacement, setup and programming

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