HVAC - Automatic
DTC B0248, B0268, B0408, B0413, B0418, B0423, B0428, B0433, B3531, B3761, B3773, or B3782
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of the diagnostic category.
DTC Descriptors
DTC B0248 61
- Air Flow Control 3 Circuit Actuator Stuck
DTC 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 B0418 61
- Temperature Control 2 Circuit Actuator Stuck
DTC B0423 06
- Temperature Control 2 Feedback Circuit Short to Ground or Open
DTC B0428 61
- Temperature Control 3 Circuit Actuator Stuck
DTC B0433 06
- Temperature Control 3 Feedback Circuit Short to Ground or Open
DTC B3531 61
- Air Flow Control 10 Circuit Actuator Stuck
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
DTC B3782 06
- Air Flow Control 10 Feedback Circuit Short to Ground or Open
Diagnostic Fault Information
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
* Ignition 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 percent or the HVAC control module detects the door position signal circuit is less than -32 percent or greater than 134 percent.
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.
Reference Information
Schematic Reference
HVAC Schematics (HVAC - Automatic)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Component Connector End Views (Connector Views)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Circuit/System Verification
Ignition ON, place the appropriate actuator through each position. The scan tool should display:
* Mode Door Panel: -16.872%, Bi Level: 16.635%, Floor: 49.485%, Defog: 82.992%, Defrost: 117.156%
* Auxiliary Mode Door Panel: 0.210%, Bi Level: 30.432%, Floor: 57.369%, Closed: 88.905%
* Auxiliary Temperature Door Max Cold: 0.210%, Max Hot: 100.074%
* Recirculation Door Recirculate: 18.606%, Outside Air: 100.074%
* Right Air Temperature Door Max Cold: 3.495%, Max Hot: 97.535%
* Left Air Temperature Door Max Cold: 3.495%, Max Hot: 97.535%
Circuit/System Testing
1. Disconnect the harness connector at the appropriate actuator.
2. Ignition OFF, test for less than 1 ohm between the low reference circuit terminal listed below and ground.
* Left Air Temperature Actuator terminal 3
* Right Air Temperature Actuator terminal 3
* Recirculation Actuator terminal 3
* Mode Actuator terminal 1
* Auxiliary Mode Actuator terminal 1
• If greater than the specified range, test the low reference circuit for a short to voltage or 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 listed below and ground.
* Left Air Temperature Actuator terminal 1
* Right Air Temperature Actuator terminal 1
* Recirculation Actuator terminal 1
* Mode Actuator terminal 3
* Auxiliary Mode Actuator terminal 3
• 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 -30 Percent.
• If greater than the specified range, test the signal circuit terminal 5 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 5 and the low reference circuit terminal listed below . Verify the appropriate scan tool parameter is greater than 130 percent.
* Left Air Temperature Actuator terminal 3
* Right Air Temperature Actuator terminal 3
* Recirculation Actuator terminal 3
* Mode Actuator terminal 1
* Auxiliary Mode Actuator terminal 1
• 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. Ignition ON, after 30 seconds verify that a test lamp illuminates between control circuit A terminal 6 and B+.
• If the test lamp does not illuminate, 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, verify that the test lamp does not illuminate between control circuit A terminal 6 and B+.
• If the test lamp illuminate, test the control circuit for a short to ground. If circuit tests normal replace the HVAC control module.
8. Ignition ON, after 30 seconds verify that a test lamp illuminates between control circuit B terminal 7 and B+.
• If the test lamp does not illuminate, test the control circuit for a short to voltage or an open/high resistance. If circuit tests normal replace the HVAC control module.
9. Ignition OFF, verify that the test lamp does not illuminate between control circuit B terminal 7 and B+.
• If the test lamp illuminate, test the control circuit for a short to ground. If circuit tests normal replace the HVAC control module.
10. If all circuits test normal, test or replace the actuator.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Recirculation Actuator Replacement (Recirculation Actuator Replacement)
* Mode Actuator Replacement (Mode Actuator Replacement)
* Temperature Valve Actuator Replacement - Left Side (Temperature Valve Actuator Replacement - Left Side)
* Temperature Valve Actuator Replacement - Right Side (Temperature Valve Actuator Replacement - Right Side)
* Defroster Valve Actuator Replacement (Defroster Valve Actuator Replacement)
* Floor Air Valve Actuator Replacement (Floor Air Valve Actuator Replacement)
* Control Module References (Programming and Relearning) for HVAC control module replacement, setup, and programming