• | 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. |
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
---|---|---|---|---|
Recirculation Door Control A Circuit | B0268 61 | B0268 61 | B0268 | B0268 4B |
Recirculation Door Control B Circuit | B0268 61 | B0268 61 | B0268 | B0268 4B |
Recirculation Door Position Signal | B0268 61 | B0268 06 | B0268 61 | B0268 4B |
Recirculation 5-Volt Reference Circuit | B0248 61, B0408 61, B0268 61 | B0268 06 | B0268 61, 06 | -- |
Recirculation Low Reference Circuit | -- | B0268 61 | -- | B0268 4B |
Air Temperature Door Control A Circuit | B0408 61 | B0408 61 | B0408 | B0408 4B |
Air Temperature Door Control B Circuit | B0408 61 | B0408 61 | B0408 | B0408 4B |
Air Temperature Door Position Signal | B0408 61 | B0408 06 | B0408 61 | B0408 4B |
Air Temperature 5-Volt Reference Circuit | B0248 61, B0408 61, B0268 61, | B0408 06 | B0408 61 | -- |
Air Temperature Low Reference Circuit | -- | B0408 61 | -- | -- |
Mode Door Control A Circuit | B0248 61 | B0248 61 | -- | B0248 4B |
Mode Door Control B Circuit | B0248 61 | B0248 61 | -- | B0248 4B |
Mode Door Position Signal | B0248 61 | B0248 61 | B0248 61 | B0248 4B |
Mode 5-Volt Reference Circuit | B0248 61, B0408 61, B0268 61, | B0248 61 | B0248 61 | -- |
Mode Low Reference Circuit | -- | B0248 61 | -- | -- |
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.
• | The ignition is ON. |
• | Ignition voltage is between 9-16 volts. |
• | The HVAC module is ON. |
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.
Driver A and driver B circuits are deactivated for the appropriate actuator.
• | 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. |
⇒ | 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. |
⇒ | 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. |
⇒ | 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. |
⇒ | 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. |
⇒ | 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. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for HVAC replacement, setup, and programming |