B104B - Understanding the Body Control Module Malfunction in Common Vehicles

Quick Answer

B104B means: B104B indicates a malfunction in the Body Control Module or its circuits.

Fix: Check and replace faulty components Cost: $400 - $800 Time: 90-180 minutes

Can I drive with B104B? Immediate attention is recommended to avoid further electrical issues.

Common Questions

What does B104B mean and how does it affect my car?

The B104B code indicates a malfunction in the Body Control Module (BCM), which controls many electrical functions in your vehicle. This can lead to issues with systems like windows, locks, and lights, affecting both convenience and safety.

What are the most common causes of B104B and how much does it cost to fix?

Common causes include BCM failure, damaged wiring, and corrosion at connectors. Repair costs vary, with BCM replacement averaging $400-$800 and wiring repairs ranging from $100-$300.

Can I drive my car with B104B or should I stop immediately?

It's advisable to avoid driving your vehicle with the B104B code since it may lead to electrical failures that could leave you stranded or compromise safety features.

How can I diagnose B104B myself using GeekOBD APP?

Using the GeekOBD APP, you can scan for diagnostic codes, review freeze frame data, and even monitor real-time data from the BCM to diagnose issues effectively.

What vehicles are most commonly affected by B104B?

The B104B code is frequently reported in 2015-2018 models of Ford Focus, Chevrolet Malibu, and Honda Accord, among others. Always check for recalls or technical service bulletins related to these models.

How can I prevent B104B from happening again?

Regular maintenance of your vehicle's electrical system, checking for corrosion at connectors, and ensuring proper sealing against moisture can help prevent B104B from recurring.

What is B104B?

The B104B diagnostic trouble code (DTC) indicates that there is a malfunction within the Body Control Module (BCM) or a related circuit. This code is commonly associated with various makes and models, particularly those from Ford, Chevrolet, and Honda manufactured between 2015 and 2018. The BCM is responsible for controlling numerous electrical systems in the vehicle, such as the power windows, door locks, interior lights, and even the anti-theft system. When the BCM detects an anomaly, it triggers the B104B code, prompting a check of the associated circuits. Car owners may experience symptoms such as malfunctioning electrical components or warning lights on the dashboard. Ignoring this code can lead to further issues, such as complete failure of the affected systems, leaving you with a vehicle that may not operate as intended. Regular diagnostics are crucial, and tools like the GeekOBD APP can facilitate a thorough scan of the vehicle’s systems, helping to pinpoint the problem more effectively. A proactive approach can save you time and money in the long run, ensuring that your vehicle remains in optimal working condition.

System: B - Body (Airbags, Lighting, Security, Climate Control)

Symptoms

Common symptoms when B104B is present:

  • Dashboard warning lights, such as the check engine or battery light, may illuminate, indicating a fault in the vehicle's electrical system.
  • Power windows and door locks may become inoperative or function intermittently, leading to frustration during daily use.
  • Interior lights may flicker or fail to turn on, affecting visibility and convenience inside the vehicle.
  • The anti-theft system may trigger unexpectedly, preventing the vehicle from starting and causing unnecessary delays.
  • In some cases, there may be a noticeable decrease in overall electrical system performance, such as dimming headlights or erratic gauge behavior.

Possible Causes

Most common causes of B104B (ordered by frequency):

  1. The most common cause of the B104B code is a failure within the Body Control Module itself, accounting for approximately 40% of cases. This may be due to internal component failure or software issues.
  2. Another frequent cause is damaged wiring or poor connections in the BCM circuit, which can result from wear and tear or exposure to moisture. This is responsible for about 30% of reported issues.
  3. Corrosion at the BCM connectors can lead to intermittent electrical faults, making it crucial to check for rust or debris during inspections. Preventing exposure to moisture can mitigate this risk.
  4. Less commonly, a failing battery or alternator can produce symptoms similar to those of B104B, particularly if the electrical system is not receiving adequate voltage.
  5. In rare instances, aftermarket modifications to the vehicle's electrical system can interfere with the BCM's operation, triggering this DTC.

B104B Repair Costs

Cost Breakdown by Repair Type

BCM Replacement

Replacing the Body Control Module if it is found to be faulty after diagnostics.

  • Total: $400 - $800
  • Success rate: 95%
Wiring Repair

Repairing damaged wiring or connections related to the BCM.

  • Total: $100 - $300
  • Success rate: 85%
Money-Saving Tips for B104B
  • Start with the most common and least expensive repairs first
  • Use GeekOBD APP to confirm diagnosis before replacing expensive parts
  • Consider preventive maintenance to avoid future occurrences
  • Compare prices for OEM vs aftermarket parts based on your needs
  • Address the issue promptly to prevent more expensive secondary damage

Diagnostic Steps

Professional B104B Diagnosis Process

Follow these systematic steps to accurately diagnose B104B. Each step builds on the previous one to ensure accurate diagnosis.

Step 1: Step 1: Initial visual inspection - Check for obvious signs like damaged wiring, loose connections, or corrosion (5-10 minutes)

Step 1: Initial visual inspection - Check for obvious signs like damaged wiring, loose connections, or corrosion (5-10 minutes). Look specifically at the wiring harness connected to the BCM.

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.
Step 2: Step 2: OBD2 scan with GeekOBD APP - Retrieve all codes and freeze frame data to understand the fault context (10-15 minutes)

Step 2: OBD2 scan with GeekOBD APP - Retrieve all codes and freeze frame data to understand the fault context (10-15 minutes). This allows you to see if other codes are present that could help diagnose the issue.

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.
Step 3: Step 3: Component testing - Use a multimeter to test the voltage and ground at the BCM and associated circuits (20-30 minutes)

Step 3: Component testing - Use a multimeter to test the voltage and ground at the BCM and associated circuits (20-30 minutes). Ensure that the BCM is receiving the correct voltage as specified in the vehicle's service manual.

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.
Step 4: Step 4: System function test - Verify the operation of electrical components controlled by the BCM after repairs and clear codes (10-15 minutes)

Step 4: System function test - Verify the operation of electrical components controlled by the BCM after repairs and clear codes (10-15 minutes). This step confirms that the issue has been resolved.

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.
Step 5: Step 5: Road test verification - Drive the vehicle under varying conditions to confirm that all systems are functioning correctly after repair (15-20 minutes)

Step 5: Road test verification - Drive the vehicle under varying conditions to confirm that all systems are functioning correctly after repair (15-20 minutes). Monitor for any reoccurrence of the symptoms.

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.

Important Notes

  • Always verify the repair with GeekOBD APP after completing diagnostic steps
  • Clear codes and test drive to ensure the problem is resolved
  • Address underlying causes to prevent code recurrence

Real Repair Case Studies

Case Study 1: BCM Replacement on 2016 Ford Focus

Vehicle: 2016 Ford Focus, 45,000 miles

Problem: Customer reported that power windows and locks were intermittently failing.

Diagnosis: After running a diagnostic scan with GeekOBD, the B104B code was detected along with some wiring issues.

Solution: Replaced the Body Control Module and repaired damaged wiring connections.

Cost: $600 (BCM: $450, Wiring repair: $150)

Result: All electrical functions were restored, and the customer reported satisfaction with the repair.

Case Study 2: Wiring Repair on 2017 Chevrolet Malibu

Vehicle: 2017 Chevrolet Malibu, 30,000 miles

Problem: Customer noticed that the interior lights would flicker and door locks would fail.

Diagnosis: Diagnostic scan revealed B104B; visual inspection showed corrosion at the BCM connector.

Solution: Cleaned the connector and replaced corroded wiring.

Cost: $200 (Labor: $100, Parts: $100)

Result: The flickering ceased, and all electrical systems functioned correctly post-repair.

Diagnose B104B

Use GeekOBD APP for professional diagnosis!

  • Real-time data monitoring
  • Advanced diagnostic features
  • Step-by-step repair guidance
  • Professional-grade analysis
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Code Information

Code: B104B
System: Body (Airbags, Lighting, Security, Climate Control)
Severity: HIGH
Category: Body Codes