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B0428




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 00
- Temperature Control 1 Feedback Circuit

DTC B0418 61
- Temperature Control 2 Circuit Actuator Stuck

DTC B0423 00
- Temperature Control 2 Feedback Circuit

DTC B0428 61
- Temperature Control 3 Circuit Actuator Stuck

DTC B0433 00
- Temperature Control 3 Feedback Circuit

DTC B3531 61
- Air Flow Control 10 Circuit Actuator Stuck

DTC B3761 00
- Air Flow Control 3 Feedback Circuit

DTC B3773 00
- Air Flow Control 7 Feedback Circuit

DTC B3782 00
- Air Flow Control 10 Feedback Circuit

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 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.

Reference Information
Schematic Reference

HVAC Schematics (Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Automatic HVAC Description and Operation (HVAC - Automatic)
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, command the appropriate actuator to 100 percent with a scan tool. The scan tool should display between 224 and 230 counts on the mode actuator, all other actuators should display between 199 and 205 counts.

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 1 and ground.

• 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 2 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 4 counts.

• 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.

5. Install a 3A fused jumper wire between the signal circuit terminal 3 and the low reference circuit terminal 1. Verify the appropriate scan tool 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. Ignition ON, after 30 seconds verify that a test lamp illuminates between control circuit A terminal 5 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 5 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 4 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 4 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.

* Air Inlet Valve Actuator Replacement (Air Inlet Valve Actuator Replacement)
* Mode Valve Actuator Replacement (Mode Valve 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)
* Auxiliary Temperature Valve Actuator Replacement (Auxiliary Temperature Valve Actuator Replacement)
* Mode Valve Actuator Replacement - Console (Mode Valve Actuator Replacement - Console)
* Control Module References (Programming and Relearning)for HVAC control module replacement, setup, and programming

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