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 (Connector Views)
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 (Programming and Relearning) 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
1. Ignition OFF, disconnect the harness connector at the appropriate actuator.
2. Ignition OFF, test for less than 5 ohm between the low reference circuit terminal 1 and ground.
• If greater than the specified value, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K33 HVAC Control Module.
3. Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal 3 and ground.
• If less than the specified range, test the 5 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K33 HVAC Control Module.
• If greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the K33 HVAC Control Module.
4. Verify the appropriate scan tool Door Position parameter is greater than 250 counts.
• If less than the specified value, test the signal circuit terminal 2 for a short to ground. If the circuit tests normal, replace the K33 HVAC Control Module.
5. Install a 3 A fused jumper wire between the signal circuit terminal 2 and the low reference circuit terminal 1. Verify the appropriate scan tool Door Position parameter is less than 5 counts.
• If greater than the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K33 HVAC Control Module.
6. If all circuits test normal, replace the appropriate actuator and verify the DTC does not reset.
• If the DTC resets, replace the K33 HVAC Control Module.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Temperature Valve Actuator Replacement (Temperature Valve Actuator Replacement)
* Air Inlet Valve Actuator Replacement (Air Inlet Valve Actuator Replacement)
* Mode Valve Actuator Replacement (Mode Valve Actuator Replacement)
* Control Module References (Programming and Relearning) for HVAC control module replacement, setup, and programming