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 Descriptors
DTC B0248 61: Air Flow Control 3 Circuit Actuator StuckDTC B0268 61: Air Flow Control 7 Circuit Actuator Stuck
DTC B0408 61: Temperature Control 1 Circuit Actuator Stuck
DTC B0413 06: Temperature Control 1 Feedback Circuit Short to Ground or Open
DTC B3761 06: Air Flow Control 3 Feedback Circuit Short to Ground or Open
DTC B3773 06: Air Flow Control 7 Feedback Circuit Short to Ground or Open
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Recirculation Door Position Signal | B0268 61 | B3773 06 | B0268 61, B3773 06 | -- |
Recirculation Door Control A | B0268 61 | B0268 61 | B0268 61 | -- |
Recirculation Door Control B | B0268 61 | B0268 61 | B0268 61 | -- |
Driver Air Temperature 5-Volt Reference | B0248 61, B0408 61, B0418 61, B0268 61 | B0413 06 | B0408 61, B0413 06 | -- |
Driver Air Temperature Door Position Signal | B0408 61 | B0413 06 | B0408 61, B0413 06 | -- |
Driver Air Temperature Door Control A | B0408 61 | B0408 61 | B0408 61 | -- |
Driver Air Temperature Door Control B | B0408 61 | B0408 61 | B0408 61 | -- |
Driver Air Temperature Low Reference | -- | B0408 61 | -- | -- |
Mode 5-Volt Reference | B0248 61, B0408 61, B0418 61, B0268 61 | B0248 61 | B0248 61, B3761 06 | -- |
Mode Door Position Signal | B0248 61 | B0248 61, B3761 06 | B0248 61, B3761 06 | -- |
Mode Door Control A | B0248 61 | B0248 61 | B0248 61 | -- |
Mode Door Control B | B0248 61 | B0248 61 | B0248 61 | -- |
Mode Low Reference | -- | B0248 61 | -- | -- |
Circuit/System Description
Mode and Temperature Actuator
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.
Recirculation Actuator
The recirculation actuator is a 3 wire bi-directional electric motor. Ignition voltage and two control circuits enable the actuator to operate. The control circuit is either grounded or opened during normal operation. When the actuator is at rest, both control circuits are grounded. In order to move the actuator, the HVAC control module grounds one of the control circuits while opening the other. If the module needs to reverse the direction of rotation, then the control circuit states are reversed.
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. |
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Manual HVAC Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Testing
B0248, B0408, B0413 or B3761
- Ignition OFF, disconnect the harness connector at the appropriate actuator.
- Ignition OFF, test for less than 1.0 ohm of resistance between the low reference circuit terminal 2 and ground.
- Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 1 and ground.
- Verify the appropriate scan tool parameter is less than 3 counts.
- Install a 3A fused jumper wire between the signal circuit terminal 3 and the 5-volt reference circuit terminal 2. Verify the appropriate scan tool actuator parameter is greater than 250 counts.
- Reconnect the harness connector at the appropriate actuator.
- Disconnect the HVAC control module.
- Install a 20 amp fused jumper wire between the appropriate control circuit terminal and 12 volts. Momentarily install a jumper wire between the appropriate control circuit terminal and ground. The actuator should move.
- If all circuits test normal, replace the HVAC control module.
| ⇒ | 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 3 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. |
Important: Apply power and ground to the actuator for no more than 2 seconds at a time or the actuator could be damaged.
Important: When performing the following tests, make sure that the device is not already at its end of travel position by switching the polarity applied to the actuator twice if the actuator did not move in one direction.
| ⇒ | If the actuator does not move in both directions, test the control circuits for a short to voltage, short to ground or an open/high resistance. If the circuits test normal, test or replace the inoperative actuator. |
B0268 or B3773
- Ignition OFF, disconnect the harness connector at the recirculation actuator.
- Ignition ON, verify a test lamp illuminates between the ignition circuit terminal 1 and ground.
- Verify a test lamp illuminates between the ignition circuit terminal 1 and the control circuit terminal 4.
- Connect a test lamp between the ignition circuit terminal 1 and the control circuit terminal 4. Cycle the recirculation switch and verify the test lamp momentarily turns OFF.
- Verify a test lamp illuminates between the ignition circuit terminal 1 and the control circuit terminal 5.
- Connect a test lamp between the ignition circuit terminal 1 and the control circuit terminal 5. Cycle the recirculation switch and verify the test lamp momentarily turns OFF.
- If all circuits test normal, test or replace the recirculation actuator.
| ⇒ | If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. |
| ⇒ | If the test lamp does not illuminate, test the control circuit for an open/high resistance. If the circuit test normal, replace the HVAC control module. |
| ⇒ | If the test lamp is always ON, test the control circuit for a short to ground. If the circuit test normal, replace the HVAC control module. |
| ⇒ | If the test lamp does not illuminate, test the control circuit for an open/high resistance. If the circuit test normal, replace the HVAC control module. |
| ⇒ | If the test lamp is always ON, test the control circuit for a short to ground. If the circuit test normal, replace the HVAC control module. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
