B2563 — Aux A/C Blower Speed 2 Circuit Failure #

Note: The code description may vary depending on the vehicle manufacturer (OEM). Always refer to OEM service information for the most accurate wording.

• Auxiliary A/C Blower Speed 2 Circuit Failure (General / SAE)
• Blower Motor Speed 2 Circuit Malfunction (Ford)
• HVAC Blower Relay 2 Control Circuit Fault (GM)
• Blower Motor Step 2 Circuit Open/Short (Chrysler)

Summary of DTC B2563 #

DTC B2563 refers to a malfunction in the electrical circuit controlling the auxiliary air conditioning (A/C) blower motor at speed setting 2. In most vehicles, the HVAC (Heating, Ventilation, and Air Conditioning) system uses different speed settings for the blower motor, managed by relays or resistors. A fault here means the system cannot properly regulate airflow at the specified speed, potentially affecting cabin comfort. This code is set when the control module detects an open, short, or abnormal voltage in the speed 2 circuit. Depending on the vehicle, this might affect rear or auxiliary climate control systems specifically.

Common Symptoms for DTC B2563 #

When the B2563 code is present, you’ll likely notice issues with the auxiliary blower motor’s operation, especially at speed 2. Sometimes, the problem may cause the entire auxiliary blower function to fail, or it may only affect one specific speed.

• No air coming from auxiliary vents at speed 2
• Blower works at all speeds except speed 2
• Blower operates intermittently or at incorrect speeds
• Unusual noises from the blower motor or relay
• HVAC warning light illuminated (on some models)
• Rear or auxiliary A/C system not cooling/heating as expected

Probable Causes for DTC B2563 #

B2563 is most often triggered by electrical issues within the blower speed control circuit. These can range from a failed resistor to wiring damage. Here are the most common underlying causes, ordered by frequency:

1. Faulty blower motor resistor (controls different speed settings)
2. Worn or faulty blower motor (especially if high mileage)
3. Open, shorted, or corroded wiring/connectors in the speed 2 circuit
4. Defective blower speed relay (if used in circuit design)
5. HVAC control module failure (less common, but possible)

Step-by-Step Diagnostic Process for DTC B2563 #

Accurate diagnosis is key for resolving B2563 without unnecessary parts replacement. Here’s a proven step-by-step approach:

• Verify the DTC with a professional-grade scan tool and clear any stored codes.
• Test the auxiliary blower motor operation at all speed settings. Note which speeds fail.
• Visually inspect wiring and connectors related to the blower motor and resistor for corrosion, damage, or loose connections.
• Check for voltage and ground at the blower motor and resistor using a multimeter, especially at speed 2.
• Test the blower motor resistor for continuity and correct resistance values per OEM specifications.
• Inspect and test the relay (if applicable) that controls speed 2 for proper operation.
• If all hardware checks out, use the scan tool to command the blower at various speeds and observe module outputs.
• As a last step, consider testing the HVAC control module if all other components are functional.

Possible Repairs for DTC B2563 #

Repairs will depend on the root cause identified during diagnosis. Here are the most common solutions:

• Replace faulty blower motor resistor or resistor pack
• Repair or replace damaged wiring/connectors in the blower speed 2 circuit
• Replace defective blower motor (if it fails only at certain speeds)
• Replace faulty blower speed relay (if present)
• Replace or reprogram the HVAC control module if found faulty

Is it Safe to Drive with DTC B2563? #

Driving with code B2563 is generally safe for short distances, as it does not directly affect engine or brake performance. However, you may experience reduced comfort due to limited climate control functionality, especially in extreme weather. Prolonged operation without repair may result in further electrical issues or discomfort for passengers.

Vehicles Most Commonly Affected by DTC B2563 #

While B2563 can appear on many makes, it’s most often reported in vehicles equipped with rear or auxiliary A/C systems. Commonly affected models include:

• Chevrolet Suburban, Tahoe, and Silverado (with rear HVAC)
• GMC Yukon and Sierra (with auxiliary A/C)
• Ford Expedition and Explorer (with rear climate control)
• Chrysler Town & Country and Dodge Grand Caravan (with rear blower)
• Cadillac Escalade (with third-row HVAC)

Frequent Mistakes & Best Practices for DTC B2563 #

Technicians and DIYers sometimes overlook simple issues or replace parts unnecessarily. Here are some common pitfalls and how to avoid them:

• Replacing the blower motor before testing the resistor or wiring
• Ignoring corroded or loose connectors, which are a frequent cause
• Not verifying power and ground at the blower circuit with a multimeter
• Overlooking the relay (if used) as a potential culprit
• Skipping a full scan of the HVAC system for related codes

Express FAQ for DTC B2563 #

Got a quick question? Here are fast answers to the most common concerns:

• Q: Will B2563 cause my A/C to stop working entirely?
  A: Not necessarily. Usually, only one speed (often speed 2) is affected, but the rest of the system may still function.
• Q: Can I just replace the fuse to fix B2563?
  A: Rarely. A blown fuse is not a common cause for this code—focus on the resistor, wiring, and relay first.