For 1990-2009 cars

## DTC B0228, B0238, B0253, B0408, B0418, B0428, or B3531 LHD

### 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 Descriptors

DTC B0228 61 : Air Intake Flow Actuator Fault
DTC B0238 61 : Demist Actuator Fault
DTC B0253 61 : Face/Floor Actuator Fault
DTC B0408 06 : Drivers Side Air Mix Actuator
DTC B0418 61 : Passenger Side Air Mix Actuator

### Circuit/System Description

The HVAC control module controls the HVAC door actuators to regulate the airflow through the HVAC system. Each actuator consists of an electric motor and a potentiometer. The module supplies a low reference and 5-volt reference source voltage to the potentiometer. The HVAC control module monitors the voltage drop across the potentiometer on the door position signal circuit. When the actuator shaft rotates, the voltage on the door position signal circuit changes. The HVAC control module supplies the actuator motor with a 12-volt control circuit and a ground control circuit. The HVAC module controls the direction of the actuator door by changing the polarity of the control circuits.

### Conditions for Running the DTC

• | The ignition is ON.

• | Ignition voltage is between 9-16 volts.

• | The HVAC module is ON.

### Conditions for Setting the DTC

The actual door position differs from the commanded door position by more than 4 counts or the HVAC control module detects the door position signal circuit is less than 7 counts or greater than 250 counts.

### Action Taken When the DTC Sets

Driver A and driver B circuits are deactivated for the appropriate actuator.

### Conditions for Clearing the DTC

• | The condition for setting the DTC is no longer present.

• | The history DTC will clear after 50 fault-free ignition cycles.

• | The DTC can be cleared with a scan tool.

### Reference Information

#### Schematic Reference

HVAC Schematics

#### Connector End View Reference

Component Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References

### Circuit/System Verification

Ignition ON, command the appropriate actuator to 100 percent with a scan tool. The scan tool should display between 224 and 230 counts on the mode actuator, all other actuators should display between 199 and 205 counts.

### Circuit/System Testing

1. Ignition OFF, test for less than 1 ohm of resistance between the low reference circuit and ground.

⇒ | If greater than 1 ohm, test the low reference circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the HVAC control module.

2. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit and ground.

⇒ | If less than 4.8 volts, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the HVAC control module.

⇒ | If greater than 5.2 volts, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the HVAC control module.

3. Verify the appropriate scan tool parameter is less than 4 counts.

⇒ | If greater than 4 counts, test the signal circuit terminal 3 for a short to ground. If the circuit tests normal, replace the HVAC Control Module.

4. Install a 3-amp fused jumper wire between the signal circuit terminal 3 and the low reference circuit terminal. Verify the appropriate scan tool parameter is greater than 250 counts.

⇒ | If less than 250 counts, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the HVAC control module.

5. Ignition ON, after 30 seconds verify that a test lamp illuminates between control circuit A terminal and B+.

⇒ | If the test lamp does not illuminate, test the control circuit for a short to voltage or an open/high resistance. If circuit tests normal replace the HVAC control module.

6. Ignition OFF, verify that the test lamp does not illuminate between control circuit A terminal and B+.

⇒ | If the test lamp illuminates, test the control circuit for a short to ground. If circuit tests normal replace the HVAC control module.

7. Ignition ON, after 30 seconds verify that a test lamp illuminates between control circuit B terminal and B+.

⇒ | If the test lamp does not illuminate, test the control circuit for a short to voltage or an open/high resistance. If circuit tests normal replace the HVAC control module.

8. Ignition OFF, verify that the test lamp does not illuminate between control circuit B terminal and B+.

⇒ | If the test lamp illuminate, test the control circuit for a short to ground. If circuit tests normal replace the HVAC control module.

9. If all circuits test normal, replace the actuator.

### Repair Instructions

Important: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | HVAC Control Module Programming and Setup .

• | Recirculation Actuator Replacement

• | Temperature Valve Actuator Replacement - Left Side

• | Temperature Valve Actuator Replacement - Right Side

• | Mode Actuator Replacement