B0268
DTC B0248, B0268, or B0408
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptors
DTC B0248 05
- Air Flow Control 3 Circuit Short to Battery or Open
DTC B0248 06
- Air Flow Control 3 Circuit Short to Ground or Open
DTC B0248 61
- Air Flow Control 3 Circuit Actuator Stuck
DTC B0248 4B
- Air Flow Control 3 Circuit Calibration Not Learned
DTC B0268 05
- Air Flow Control 7 Feedback Circuit Short to Battery or Open
DTC B0268 06
- Air Flow Control 7 Circuit Short to Ground or Open
DTC B0268 61
- Air Flow Control 7 Circuit Actuator Stuck
DTC B0268 4B
- Air Flow Control 7 Feedback Circuit Calibration Not Learned
DTC B0408 4B
- Temperature Control 1 Feedback Circuit Calibration Not Learned
DTC B0408 05
- Air Flow Control 7 Circuit Short to Battery or Open
DTC B0408 06
- Temperature Control 1 Circuit Short to Ground or Open
DTC B0408 61
- Temperature Control 1 Circuit Actuator Stuck
Diagnostic Fault Information
Circuit/System Description
The HVAC control module controls the HVAC door actuator to regulate the airflow through the HVAC system. The 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 DTC becomes history when the HVAC control module no longer detects the condition that set the DTC.
* The history DTC will clear after 50 fault free ignition cycles.
* The DTC can be cleared with a scan tool.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the appropriate actuator.
2. Ignition OFF, test for less than 1.0 ohm of resistance between the low reference circuit terminal 10 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 8 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 parameter is less than 3 counts.
• If greater than the specified range, test the signal circuit terminal 9 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 9 and the low reference circuit terminal 10. Verify the appropriate scan tool actuator parameter is greater than 250 counts.
• If less 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. Connect a test lamp between control circuit terminal 5 and control circuit terminal 6.
7. Command the actuator in both directions with a scan tool. The test lamp should turn ON and OFF with each command.
• If the test lamp remains always ON or always OFF during either of the commands, test for an open, short to ground or short to voltage on either control circuit. If the circuits test normal, replace the HVAC control module.
8. If all circuits test normal, replace the actuator.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests
* Recirculation Actuator Replacement
* Mode Actuator Replacement
* Air Temperature Actuator Replacement
* Control Module References for HVAC replacement, setup, and programming