Diagnostic Instructions

DTC Descriptors

DTC B0228 02: Recirculate Position Feedback Circuit Short to Ground

DTC B0228 05: Recirculate Position Feedback Circuit Short to Battery or Open

DTC B0228 61: Recirculate Position Circuit Actuator Stuck

DTC B0423 02: Temperature Control 2 Feedback Circuit Short to Ground

DTC B0423 05: Temperature Control 2 Feedback Circuit Short to Battery or Open

DTC B0423 61: Temperature Control 2 Feedback Circuit Actuator Stuck Open

DTC B3779 02: Air Flow Control 9 Feedback Circuit Short to Ground

DTC B3779 05: Air Flow Control 9 Feedback Circuit Short to Battery or Open

DTC B3779 61: Air Flow Control 9 Circuit Actuator Stuck

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Recirculation Door Control A	B0228 02	B0228 05	B0228 05	B0228 61
Recirculation Door Control B	B0228 02	B0228 05	B0228 05	B0228 61
Recirculation Door Position Signal	B0228 02	B0228 05	B0228 05	B0228 61
Recirculation 5-Volt Reference	B0423 02, B0228 02, B3779 02	B0228 05	B0423 02, B0228 02, B3779 02	B0228 61
Recirculation Low Reference	B0228 02	B0228 05	B0228 05	B0228 61
Air Temperature Door Control A	B0423 02	B0423 05	B0423 05	B0423 61
Air Temperature Door Control B	B0423 02	B0423 05	B0423 05	B0423 61
Air Temperature Door Position Signal	B0423 02	B0423 05	B0423 05	B0423 61
Air Temperature 5-Volt Reference	B0423 02, B0228 02, B3779 02	B0423 05	B0423 02, B0228 02, B3779 02	B0423 61
Air Temperature Low Reference	B0423 02	B0423 05	B0423 05	B0423 61
Mode Door Control A	B3779 02	B3779 05	B3779 05	B3779 61
Mode Door Control B	B3779 02	B3779 05	B3779 05	B3779 61
Mode Door Position Signal	B3779 02	B3779 05	B3779 05	B3779 61
Mode 5-Volt Reference	B0423 02, B0228 02, B3779 02	B3779 05	B0423 02, B0228 02, B3779 02	B3779 61
Mode Low Reference	B3779 02	B3779 05	B3779 05	B3779 61

Circuit/System Description

The actuators operate using 5 circuits. A 5-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 5-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

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 3 counts or greater than 253 counts.

Action Taken When the DTC Sets

The control circuit is deactivated for the appropriate actuator.

Conditions for Clearing the DTC

Reference Information

Schematic Reference

HVAC Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Ignition ON, command the appropriate actuator in both directions with a scan tool. The scan tool Door Position parameter reading should be between 5 and 250 counts.

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 1 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 4.8-5.2 volts between the 5-volt reference circuit terminal 3 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 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the HVAC control module.

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

⇒	If less than the specified range, test the signal circuit terminal 2 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 2 and the low reference circuit terminal 1. Verify the appropriate 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 4 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 5 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 5 and control circuit terminal 4.
9. 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

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.