B0418
DTC B0238, B0239, B0248-B0250, B0268, B0269, B0408, B0409, B0414, B0418, B0419, B0424, B0428, B0429, B0434, B3532, B3747-B3749, 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 each diagnostic category.
DTC Descriptors
DTC B0238
- Air Flow Control 1 Defrost Circuit- Defrost Actuator
DTC B0239
- Air Flow Control 1 Defrost Circuit Range/Performance- Auxiliary Mode Actuator
DTC B0248
- Air Flow Control 3 Blend Defog and Floor Circuit- Mode Actuator
DTC B0249
- Air Flow Control 3 Blend Defog and Floor Circuit Range/Performance- Mode Actuator
DTC B0250
- Air Flow Control 3 Blend Defog and Floor Circuit Low- Defrost Actuator
DTC B0268
- Air Flow Control 7 Recirculate Circuit- Recirculation Actuator
DTC B0269
- Air Flow Control 7 Recirculate Circuit Range/Performance- Recirculation Actuator
DTC B0408
- Temperature Control Left Circuit- Left Temperature Actuator
DTC B0409
- Temperature Control Left Circuit Range/Performance- Left Temperature Actuator
DTC B0414
- Temperature Control Left Feedback Circuit Range/Performance- Left Temperature Actuator
DTC B0418
- Temperature Control 2 Passenger Circuit- Right Temperature Actuator
DTC B0419
- Temperature Control 2 Passenger Circuit Range/Performance- Right Temperature Actuator
DTC B0424
- Temperature Control 2 Passenger Feedback Circuit Range/Performance- Right Temperature Actuator
DTC B0428
- Temperature Control 3 Rear Circuit- Auxiliary Temperature Actuator
DTC B0429
- Temperature Control 3 Rear Circuit Range/Performance- Auxiliary Temperature Actuator
DTC B0434
- Temperature Control 3 Rear Feedback Circuit Range/Performance- Auxiliary Temperature Actuator
DTC B3532
- Air Flow Control 10 Rear Circuit Range/Performance- Auxiliary Mode Actuator
DTC B3747
- Air Flow Control 1 Defrost Feedback Circuit Range/Performance- Defrost Actuator
DTC B3748
- Air Flow Control 3 Blend Defog and Floor Feedback Circuit Range/Performance- Mode Actuator
DTC B3749
- Air Flow Control 7 Recirculate Feedback Circuit Range/Performance- Recirculation Actuator
DTC B3782
- Air Flow Control 10 Rear Feedback Circuit- Auxiliary Mode Actuator
Diagnostic Fault Information
Circuit/System Description
The HVAC control module controls the HVAC actuators to regulate the airflow and temperature through the HVAC system. The actuators are 2-wire, bi-directional electric motors that share the same common control circuit. When the operator adjusts the actuators, the control module can only operate one actuator at a time due to the shared common control circuit. The control circuits use either a 0 or 12-volt value to coordinate the actuator movement. The HVAC control module reverses the polarity of the control circuits to move the actuator in the opposite direction.
The HVAC control module determines the door position by counting motor pulses on one of the control circuits. The HVAC control module converts the pulses to counts with a range of 0-255 counts.
When a calibration or recalibration procedure is performed, the HVAC control module calculates the door travel range. The HVAC control module compares the total number of pulses to calibrated limits. If the total pulse count is less than or equal to the maximum calibrated limited and more than or equal to the minimum calibrated limit, then the calibration is considered successful.
Conditions for Running the DTC
* The ignition is 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
* The HVAC control module will substitute a default range value.
* The HVAC control module will no longer issue commands to the actuator if its run timer expires during the calibration/recalibration event.
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.
Diagnostic Aids
Inspect the appropriate actuator door for the following conditions:
* A misaligned actuator.
* Broken or binding linkages.
* An obstruction that prevents the appropriate actuator door from operating within its full range of motion.
* Missing seals to the actuator door.
* Misaligned seals to the actuator door
Reference Information
Schematic Reference
HVAC Schematics (Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
* Air Temperature Description and Operation (Air Temperature Description and Operation)
* Air Delivery Description and Operation (Air Delivery Description and Operation)
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, observe the operation of the drive shaft of the appropriate actuator while using the appropriate control switch. The drive shaft of the actuator should rotate.
Circuit/System Testing
1. Ignition OFF, disconnect harness connector at the appropriate actuator.
2. Verify the appropriate scan tool parameter is less than 4 counts.
• If greater than 4 counts, test the control circuit for a short to ground. If the circuit tests normal, replace the HVAC control module
3. Install a 3-amp fused jumper wire between the appropriate actuator control circuit terminal 1 and the common door control circuit terminal 6. Verify the appropriate scan tool parameter is greater than 250 counts.
• If less than 250 counts, test the actuator control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the HVAC control module.
4. If all circuits test normal, replace the actuator.
Component Testing
1. Install a 10-amp fused jumper wire between the control terminal 1 and 12 volts. Momentarily install a jumper wire between the common door control terminal 6 and ground. The appropriate actuator shaft should rotate.
• If the function does not perform as specified, replace the appropriate actuator.
2. Reverse the jumper wires; the appropriate actuator shaft should rotate.
• If the function does not perform as specified, replace the appropriate actuator.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Air Temperature Actuator Replacement (Single Zone) (Air Temperature Actuator Replacement (Single Zone))
* Air Temperature Actuator Replacement - Right Side (Dual Zone) (Air Temperature Actuator Replacement - Right Side (Dual Zone))
* Air Temperature Actuator Replacement - Left Side (Dual Zone) (Air Temperature Actuator Replacement - Left Side (Dual Zone))
* Defroster Actuator Replacement (Defroster Actuator Replacement)
* Mode Actuator Replacement (Mode Actuator Replacement)
* Recirculation Actuator Replacement (Recirculation Actuator Replacement)
* Control Module References (Programming and Relearning)for HVAC replacement, setup, and programming