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HVAC - Automatic




DTC B0228, B0413, B0423, or B3779

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.

* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

B0228 02
- Recirculation Position Feedback Circuit Short to Ground

B0228 04
- Recirculation Position Feedback Circuit Open

B0228 05
- Recirculation Position Feedback Circuit Short to Battery or Open

B0228 61
- Recirculation Position Circuit Actuator Out of Range

B0413 02
- Temperature Control 1 Feedback Circuit Short to Ground

B0413 04
- Temperature Control 1 Feedback Circuit Actuator Stuck

B0413 05
- Temperature Control 1 Feedback Circuit Short to Battery or Open

B0413 61
- Temperature Control 1 Feedback Circuit Actuator out of Range

B0423 02
- Temperature Control 2 Feedback Circuit Short to Ground

B0423 04
- Temperature Control 2 Feedback Circuit Open

B0423 05
- Temperature Control 2 Feedback Circuit Short to Battery or Open

B0423 61
- Temperature Control 2 Circuit Actuator Out of Range

B3779 02
- Air Flow Control 9 Feedback Circuit Short to Ground

B3779 04
- Air Flow Control 9 Feedback Circuit Open

B3779 05
- Air Flow Control 9 Feedback Circuit Short to Battery or Open

B3779 61
- Air Flow Control 9 Circuit Actuator Out of Range

Diagnostic Fault Information






Circuit/System Description

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 V 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 control circuit uses either a 0, 2.5 or 5 V signal to command the actuator movement. When the actuator is at rest, the control circuit value is 2.5 V. When actuator movement is commanded in one direction the voltage toggles between 2.5-5 V, then, when commanded in the opposite direction the voltage toggles between 2.5-0 V.

* B0228 is for the recirculation actuator.

* B0413 is for the drivers air temperature actuator.

* B0423 is for the passenger air temperature actuator.

* B3779 is for the mode actuator.

Conditions for Running the DTC

* Ignition ON.

* 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 3 counts or greater than 253 counts.

Action Taken When the DTC Sets

The control circuit is 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 100 fault-free ignition cycles have occurred.

Diagnostic Aids

Not all intermittent conditions will cause a DTC to be stored.

Reposition tightly pulled wire harness actuator connections to relieve taught wires at connectors, and apply dielectric grease to actuator terminals to eliminate/minimize intermittent conditions.

Wiggle the harness near the connector to inspect terminal joints for loose connections.

Reference Information

Schematic Reference

HVAC Schematics HVAC - Automatic

Connector End View Reference

Component Connector End Views 1-2 Shift Solenoid (SS) Valve (M30)

Description and Operation

* Air Delivery Description and Operation Air Delivery

* Air Temperature Description and Operation Air Temperature

Electrical Information Reference

* Circuit Testing Circuit Testing

* Connector Repairs Connector Repairs

* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections

* Wiring Repairs Wiring Repairs

Scan Tool Reference

Control Module References Control Module References for scan tool information

Circuit/System Verification

Ignition ON, command the appropriate actuator in both directions with a scan tool. The scan tool door position parameter reading should be between 3 and 253 counts.

Circuit/System Testing

Note: Refer to bulletin 09-06-03-004 before replacing any components.

1. Ignition OFF, disconnect the harness connector at the appropriate actuator.

2. Test for less than 40 ohms between the low reference circuit terminal 7 and ground.

• If 40 ohms or greater

1. Ignition OFF, disconnect the X3 harness connector at the HVAC control module.

2. Test for less than 2 ohms in the low reference circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.

• If less than 2 ohms, replace the HVAC control module.

• If less than 40 ohms

3. Ignition ON.

4. Verify that a test lamp illuminates between the ignition circuit terminal 5 and ground.

• If the test lamp does not illuminate and the circuit fuse is good

1. Ignition OFF.

2. Test for less than 2 ohms in the ignition circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.

• If less than 2 ohms, verify the fuse is OK and there is voltage at the fuse.

• If the test lamp does not illuminate and the circuit fuse is open

1. Ignition OFF.

2. Test for infinite resistance between the ignition circuit and ground.

• If less than infinite resistance, repair the short to ground on the circuit.

• If infinite resistance, replace the actuator.

• If the test lamp illuminates

5. Test for 4.8-5.2 V between the 5 V reference circuit terminal 10 and ground.

• If less than 4.8 V

1. Ignition OFF, disconnect the X3 harness connector at the HVAC control module.

2. Test for infinite resistance between the 5 V reference circuit and ground.

• If less than infinite resistance, repair the short to ground on the circuit.

• If infinite resistance

3. Test for less than 2 ohms in the 5 V reference circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.

• If less than 2 ohms, replace the HVAC control module.

• If greater than 5.2 V

1. Ignition OFF, disconnect the X3 harness connector at the HVAC control module, ignition ON.

2. Test for less than 1 V between the 5 V reference circuit and ground.

• If 1 V or greater, repair the short to voltage on the circuit.

• If less than 1 V, replace the HVAC control module.

• If between 4.8-5.2 V

6. Verify the appropriate scan tool parameter listed below is greater than 250 counts:

* Mode Door Actual

* Right Temp. Dr. Actual

* Air Inlet. Dr. Actual

* Left Temp. Dr. Actual

• If 250 counts or less

1. Ignition OFF, disconnect the harness connector at the HVAC control module.

2. Test for infinite resistance between the signal circuit and ground.

• If less than infinite resistance, repair the short to ground on the circuit.

• If infinite resistance, replace the HVAC control module.

• If greater than 250 counts

7. Install a 3 A fused jumper wire between the signal circuit terminal 9 and the low reference circuit terminal 7.

8. Verify the appropriate scan tool parameter listed below is less than 5 counts.

* Mode Door Actual

* Right Temp. Dr. Actual

* Air Inlet Dr. Actual

* Left Temp. Dr. Actual

• If 5 counts or greater

1. Ignition OFF, disconnect the X3 harness connector at the HVAC control module, ignition ON.

2. Test for less than 1 V between the signal circuit and ground.

• If 1 V or greater, repair the short to voltage on the circuit.

• If less than 1 V

3. Ignition OFF.

4. Test for less than 2 ohms in the signal circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.

• If less than 2 ohms, replace the HVAC control module.

• If less than 5 counts

9. Test for 2.2-2.8 V between the control circuit terminal 6 and ground.

• If less than 2.2 V

1. Ignition OFF, disconnect the X3 harness connector at the HVAC control module.

2. Test for infinite resistance between the control circuit and ground.

• If less than infinite resistance, repair the short to ground on the circuit.

• If infinite resistance

3. Test for less than 2 ohms in the control circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.

• If less than 2 ohms, replace the HVAC control module.

• If greater than 2.8 V

1. Ignition OFF, disconnect the X3 harness connector at the HVAC control module, ignition ON.

2. Test for less than 1 V between the control circuit and ground.

• If 1 V or greater, repair the short to voltage on the circuit.

• If less than 1 V, replace the HVAC control module.

• If between 2.2-2.8 V

10. Verify the voltage reading toggles when commanding the appropriate actuator listed below in both directions with a scan tool.

* Air Inlet Door

* Left Temp. Door Position

* Mode Door Position

* Right Temp. Door Position

• If the voltage does not toggle
Replace the HVAC control module.

• If voltage toggles

11. Test or replace the actuator.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the repair.

* 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

* Control Module References Control Module References for HVAC control module replacement, programming and setup

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