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HVAC - Automatic




DTC B0228, B0413, B1395, or B374A

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

DTC B0228 02
- Left Recirculate Position Feedback Circuit Short to Ground

DTC B0228 05
- Left Recirculate Position Feedback Circuit High Voltage/Open

DTC B0413 02
- Main Temperature Control Feedback Circuit Short to Ground

DTC B0413 05
- Main Temperature Control Feedback Circuit High Voltage/Open

DTC B1395 03
- Control Module Voltage Reference Output Circuit Low Voltage

DTC B1395 07
- Control Module Voltage Reference Output Circuit High Voltage

DTC B374A 02
- Air Flow Control Feedback Circuit Short to Ground

DTC B374A 05
- Air Flow Control Feedback Circuit High Voltage/Open

Diagnostic Fault Information






Circuit/System Description

The actuators are 5-wire bi-directional electric motors that incorporate a feedback potentiometer. Low reference, 5V reference, position signal, and 2 control circuits enable the actuator to operate. The control circuits use either a 0 or 12 V value to coordinate the actuator movement. When the actuator is at rest, both control circuits have a value of 0 V. In order to move the actuator, the HVAC control module grounds one of the control circuits while providing the other with 12 V. The HVAC control module reverses the polarity of the control circuits to move the actuator in the opposite direction. When the actuator shaft rotates, the potentiometers adjustable contact changes the door position signal between 0-5 V. The HVAC control module uses a range of 0-255 counts to index the actuator position. The door position signal voltage is converted to a 0-255 count range. When the module sets a commanded, or targeted, value, one of the control circuits is grounded. As the actuator shaft rotates the changing position signal is sent to the module. Once the position signal and the commanded value are the same, the module removes power and ground from the control circuits.

Conditions for Running the DTC

* Ignition ON.

* The HVAC control module is ON.

Conditions for Setting the DTC

B0228 02, B0413 02 or B374A 02

The HVAC control module detects the sensor signal out of range. The signal voltage is less than 0.1 V for more than 50 ms.

B0228 05, B0413 05 or B374A 05

The HVAC control module detects the sensor signal out of range. The signal voltage is greater than 4.9 V for more than 50 ms.

B1395 03

The HVAC control module detects the sensor reference voltage out of range. The reference voltage is less than 0.1 V for more than 50 ms.

B1395 07

The HVAC control module detects the sensor reference voltage out of range. The reference voltage is greater than 4.9 V for more than 50 ms.

Action Taken When the DTC Sets

B1395

* The affected output will be switched off for hardware protection.

* All actuators are deactivated.

B0228, B0413, or B374A

* The affected output will be switched off for hardware protection.

* The affected actuator is deactivated.

Conditions for Clearing the DTC

The condition for setting the DTC is no longer present.

Reference Information

Schematic Reference

HVAC Schematics HVAC - Automatic

Connector End View Reference

Component Connector End Views Sunshade - Left Front

Description and Operation

Automatic HVAC Description and Operation HVAC - Automatic

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 5-250 counts.

Circuit/System Testing

DTC B1395

1. Ignition OFF, disconnect the harness connector at the components listed below:

* B160 windshield temperature and inside moisture sensor

* M37 mode door actuator

* M46 air recirculation door actuator

* M6 air temperature door actuator

2. Disconnect the X3 harness connector at the K33 HVAC control module, ignition ON.

3. Test for less than 1 V between the K33 HVAC control module 5 V reference circuit terminals listed below and ground:

* Terminal 10 X3

* Terminal 20 X3

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

• If less than 1 V

4. Ignition OFF.

5. Test for infinite resistance between the K33 HVAC control module 5 V reference circuit terminals listed below and ground:

* Terminal 10 X3

* Terminal 20 X3

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

• If infinite resistance

6. Clear all DTCs, connect the X3 harness connector at the K33 HVAC control module, ignition ON.

7. Verify DTC B1395 is not set.

• If the DTC is set.
Replace the K33 HVAC control module.

• If the DTC is not set.

8. Verify DTC B1395 does not set after connecting each of the components listed below, one at a time:

* B160 windshield temperature and inside moisture sensor

* M37 mode door actuator

* M46 air recirculation door actuator

* M6 air temperature door actuator

• If the DTC sets after connecting one of the components
Replace the component that was connected immediately before the DTC set.

• If the DTC does not set

9. All OK.

DTC B0228, B0413, or B374A

1. Ignition OFF and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down.

2. Test for less than 10 ohms between the low reference circuit terminal 1 and ground.

• If 10 ohms or greater

1. Ignition OFF, disconnect the harness connector at the K33 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 K33 HVAC control module.

• If less than 10 ohms

3. Ignition ON.

4. Test for 4.8-5.2 V between the 5 V reference circuit terminal 3 and ground.

• If less than 4.8 V

1. Ignition OFF, disconnect the harness connector at the K33 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 K33 HVAC.

• If greater than 5.2 V

1. Ignition OFF, disconnect the harness connector at the K33 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 K33 HVAC.

• If between 4.8-5.2 V

5. Ignition ON.

6. Verify the scan tool Door Position parameter is less than 5 counts.

• If 5 counts or greater

1. Ignition OFF, disconnect the harness connector at the K33 HVAC control module, ignition ON.

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

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

• If less than 1 V, replace the K33 HVAC control module.

• If less than 5 counts

7. Install a 3 A fused jumper wire between the signal circuit terminal 2 and the 5 V reference circuit terminal 3.

8. Verify the scan tool Door Position parameter is greater than 250 counts.

• If 250 counts or less

1. Ignition OFF, disconnect the harness connector at the K33 HVAC control module.

2. Test for infinite resistance between the signal circuit terminal 2 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 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 K33 HVAC control module.

• If greater than 250 counts.

9. Replace the actuator.

Repair Instructions

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

* HVAC Component Replacement Reference HVAC Component Replacement Reference

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

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