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 Descriptor
DTC B0233: Air Flow Control CircuitDiagnostic Fault Information
Circuit | Short to Ground | High Resistance | Open | Short to Voltage |
|---|---|---|---|---|
Mode Door Control Circuit A | 1 | 1 | 1 | 1 |
Mode Door Control Circuit B | 1 | 1 | 1 | 1 |
5-Volt Reference | B0233 00 | B0233 00 | B0233 00 | B0233 00 |
Mode Door Position Signal | -- | 1 | 1 | 1 |
Mode Door Actuator Low Reference | 1 | 1 | -- | |
B+ Circuit of the HVAC Control Module | 1 | 1 | 1 | -- |
Ground Circuit of the HVAC Control Module | -- | 1 | 1 | -- |
1. Mode Door Actuator Inoperative | ||||
Circuit Description
The mode actuator is an electronic device that incorporates a stepper motor and feedback potentiometer. The HVAC control module controls the mode door position by sending a control signal to the actuator. The signal value is dependent upon the desired mode selected by the vehicle occupants. As the actuator moves, the potentiometer produces the actual door position signal that is sent to the HVAC control module. The HVAC control module continues to command the actuator to move until the desired and actual values are equal. The door directs airflow through the outlets as selected by the vehicles occupants.
The HVAC control module commands the actuator through it's full range. The HVAC control module stores the learned minimum and maximum position values. The travel range value is calculated by subtracting the minimum and maximum position values. Then the HVAC control module compares the travel range, minimum and maximum values to calibrated value ranges. If the travel range value is less than or equal to the maximum calibrated limit and greater than or equal to the minimum calibrated limit, then the calibration is considered successful. The HVAC control module continuously compares the actual actuator position to the calibrated minimum and maximum position values.
Conditions for Running the DTC
| • | The ignition is ON. |
| • | Ignition voltage is between 9-16 volts. |
Conditions for Setting the DTC
| • | Mode actuator position signal is less than 3 counts. |
| • | Mode actuator position signal is more than 250 counts. |
| • | The mode actuators total travel range is less than or greater than the calibrated limits. |
Action Taken When the DTC Sets
| • | The DTC is stored in DTC information. |
| • | The HVAC control module will continue to make use of whatever travel range is still available. |
Conditions for Clearing the DTC
| • | If the HVAC control no longer detects a failure, then the DTC will become history. |
| • | The history DTC will clear after 50 ignition cycles without a failure. |
| • | The DTC can be cleared with a scan tool. |
Circuit/System Testing
- Ignition OFF, disconnect the Mode actuator harness connector at the Mode actuator.
- Test for less than 1.0 ohm between the low reference circuit terminal 8 and ground.
- Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 10 and ground.
- Verify the appropriate scan tool parameter is less than 3 counts.
- Install a 3A fused jumper wire between the signal circuit terminal 9 and the low reference circuit terminal 8. Verify the appropriate scan tool actuator parameter is greater than 250 counts.
- Connect a test lamp between control circuit A terminal 6 and control circuit B terminal 5.
- Command the actuator in both directions with a scan tool. The test lamp should turn ON and OFF with each command.
- If all circuits test normal, replace the Mode actuator.
| ⇒ | 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 commands, test for an open, short to ground, or short to voltage on either control circuit. If the circuit tests normal, replace the HVAC control module. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for HVAC control module replacement, setup, and programming |
