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

Diagnostic Instructions

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

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

Reference Information

Schematic Reference

HVAC Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

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.

DTC B0228, B0238, B0253, B0408, B0418, B0428, or B3531 RHD

Diagnostic Instructions

DTC Descriptors

DTC B0228 29 : Recirculation Door Motor Circuit Too Few Pulses

DTC B0228 2A : Recirculation Door Motor Circuit Too Many Pulses

DTC B0228 61 : Recirculation Door Motor Circuit Stuck

DTC B0238 29 : Defogger Door Motor Circuit Too Few Pulses

DTC B0238 2A : Defogger Door Motor Circuit Too Many Pulses

DTC B0238 61 : Defogger Door Motor Circuit Stuck

DTC B0253 29 : Vent/Floor Door Motor Circuit Too Few Pulses

DTC B0253 2A : Vent/Floor Door Motor Circuit Too Many Pulses

DTC B0253 61 : Vent/Floor Door Motor Circuit Stuck

DTC B0408 29 : Drivers Air Mix Door Motor Circuit Too Few Pulses

DTC B0408 2A : Drivers Air Mix Door Motor Circuit Too Many Pulses

DTC B0408 61 : Drivers Air Mix Door Motor Circuit Stuck

DTC B0418 29 : Passengers Air Mix Door Motor Circuit Too Few Pulses

DTC B0418 2A : Passengers Air Mix Door Motor Circuit Too Many Pulses

DTC B0418 61 : Passengers Air Mix Door Motor Circuit Stuck

DTC B0428 29 : Rear Air Mix Door Motor Circuit Too Few Pulses

DTC B0428 2A : Rear Air Mix Door Motor Circuit Too Many Pulses

DTC B0428 61 : Rear Air Mix Door Motor Circuit Stuck

DTC B3531 29 : Rear Air Mode Door Motor Circuit Too Few Pulses

DTC B3531 2A : Rear Air Mode Door Motor Circuit Too Many Pulses

DTC B3531 61 : Rear Air Mode Door Motor Circuit Stuck

Circuit/System Description

The actuators operate using 5 circuits. A 12-volt reference, low reference, signal circuit and two bi-directional 0 or 12 volt control circuits. The HVAC control module supplies a low reference and 12-volt reference to the potentiometer. The HVAC control module monitors the voltage drop across the potentiometer on the door position signal circuit. As the actuator door changes position the door position signal circuit voltage also changes. The two bi-directional control circuits enable the actuator to operate. Both circuits are set to 0 volts when the HVAC control module detects, from the feedback potentiometer, that the actuator is in the desired position. In order to move the actuator, the HVAC control module switches the appropriate control circuit to 12 volts.

Conditions for Running the DTC

Conditions for Setting the DTC

Sub Code: 29

Sub Code: 2A

Sub Code: 61

Action Taken When the DTC Sets

Conditions for Clearing the DTC

Reference Information

Schematic Reference

HVAC Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

Scan Tool Reference

Control Module References

Circuit/System Verification

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the appropriate actuator.
2. Ignition OFF, test for less than 10 ohms between the low reference circuit terminal 3 and ground.

⇒	If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the HVAC control module.

3. Ignition ON, test for 11.5-13.5 volts between the 12-volt reference circuit terminal 5 and ground.

⇒	If less than the specified range, 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 the specified range, test the 12-volt reference circuit for a short to voltage. If the circuit tests normal, replace the HVAC control module.

4. Verify the scan tool Door Position parameter is greater than 250 counts.

⇒	If less than the specified range, test the signal circuit terminal 4 for a short to ground. If the circuit tests normal, replace the HVAC control module.

5. Install a 3A fused jumper wire between the signal circuit terminal 4 and the low reference circuit terminal 3. Verify the scan tool Door Position parameter is less than 3 counts.

⇒	If greater than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the HVAC control module.

6. Ignition OFF, test for less than 10 ohms between the control circuit terminal 1 and ground.

⇒	If greater than the specified range, test the control circuit for a short to voltage or an open/high resistance. If circuit tests normal, replace the HVAC control module.

7. Ignition OFF, test for less than 10 ohms between the control circuit terminal 2 and ground.

⇒	If greater than the specified range, test the control circuit for a short to voltage or an open/high resistance. If circuit tests normal, replace the HVAC control module.

8. Connect a test lamp between control circuit terminal 1 and control circuit terminal 2.
9. Ignition ON, command the appropriate actuator door in both directions with a scan tool. The test lamp should turn ON and OFF when commanded in both directions.

⇒	If the test lamp remains OFF during either of the commands, test for a short to ground on either control circuit. If the circuits test normal, replace the HVAC control module.

10. If both circuits test normal, test or replace the actuator.

Repair Instructions

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