U0843 - Lost Communication with Body Control Module (BCM), Common in 2008-2015 Chevrolet Silverado

Quick Answer

U0843 means: U0843 indicates lost communication with the Body Control Module, affecting various electrical functions.

Fix: Check and replace faulty components Cost: $300 - $800 Time: 90-180 minutes

Can I drive with U0843? While not immediately dangerous, it is advisable to address the issue promptly to prevent further electrical complications.

Common Questions

What does U0843 mean and how does it affect my car?

The U0843 code indicates a lost communication issue with your Body Control Module (BCM). This can lead to various electrical failures, such as unresponsive power windows or door locks, affecting your vehicle's convenience and safety.

What are the most common causes of U0843 and how much does it cost to fix?

Common causes include a faulty BCM, damaged wiring, and software glitches. Repair costs can vary significantly, ranging from $100 for wiring repairs to $800 for BCM replacement, depending on the specific issue.

Can I drive my car with U0843 or should I stop immediately?

While it's usually safe to drive with the U0843 code, it's not advisable to ignore it. The communication issue may lead to more significant electrical problems over time, so addressing it promptly is recommended.

How can I diagnose U0843 myself using GeekOBD APP?

Using the GeekOBD APP, you can scan your vehicle for the U0843 code. Look for freeze frame data to understand when the issue occurred, and use the app’s features to monitor BCM performance and check for related codes.

What vehicles are most commonly affected by U0843?

The U0843 code is often found in vehicles like the 2008-2015 Chevrolet Silverado and GMC Sierra, as well as other GM models from that era. It's advisable to check for any recalls or Technical Service Bulletins (TSBs) related to BCM issues.

How can I prevent U0843 from happening again?

Regular maintenance, such as inspecting wiring and connections, ensuring software updates are performed, and avoiding aftermarket modifications that tap into the vehicle's electrical systems can help prevent future U0843 occurrences.

What is U0843?

The U0843 diagnostic trouble code (DTC) signifies a lost communication issue between the vehicle's control modules, particularly with the Body Control Module (BCM). This can result in the BCM failing to send or receive signals from other modules within the vehicle's network, leading to various electrical problems. In practical terms, this could mean that features controlled by the BCM, such as power windows, door locks, and interior lighting, may not function properly. The U0843 code is particularly prevalent in models like the 2008-2015 Chevrolet Silverado and GMC Sierra, where users report problems like unresponsive window controls and malfunctioning keyless entry systems. This code triggers when the Engine Control Module (ECM) detects that the BCM is not communicating as expected, often due to wiring issues, module failures, or software glitches. Understanding this code is crucial, as ignoring it can lead to further electrical malfunctions and may affect the vehicle's overall functionality and safety. Vehicle owners should be aware that while the U0843 code itself may not directly impact engine performance, the resulting electrical issues can lead to significant inconvenience and safety concerns.

System: U - Network (Communication, CAN Bus)

Symptoms

Common symptoms when U0843 is present:

  • Check engine light and BCM warning light illuminated, indicating a communication issue.
  • Power windows and door locks do not respond to controls, leaving you unable to access your vehicle easily.
  • Intermittent failure of interior lighting or dashboard indicators, creating confusion while driving at night.
  • Keyless entry system may fail to unlock doors, making it inconvenient to enter and exit your vehicle.
  • Erratic operation of other electronic accessories, such as the radio or climate control system.

Possible Causes

Most common causes of U0843 (ordered by frequency):

  1. The most common cause of the U0843 code is a faulty Body Control Module itself, which has a likelihood of about 40%. This may be due to internal failures or programming issues.
  2. Another common cause is damaged wiring or poor connections between the BCM and other modules, which accounts for around 30% of cases. Corrosion or frayed wires can disrupt communication.
  3. A third potential cause is software glitches in the vehicle's control systems. Keeping software up-to-date can help prevent these issues.
  4. Less common but serious causes include battery or alternator issues that can affect voltage supply to the BCM, potentially leading to erratic behavior.
  5. In rare cases, aftermarket accessories that tap into the vehicle's wiring can introduce faults, leading to communication errors.

U0843 Repair Costs

Cost Breakdown by Repair Type

BCM Replacement

Replacing the faulty Body Control Module with a new or refurbished unit, including reprogramming.

  • Total: $300 - $800
  • Success rate: 85%
Wiring Repair

Repairing or replacing damaged wiring and connectors to restore communication.

  • Total: $100 - $300
  • Success rate: 70%
Software Update

Updating the vehicle's software to eliminate glitches causing communication issues.

  • Total: $50 - $150
  • Success rate: 60%
Money-Saving Tips for U0843
  • 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 U0843 Diagnosis Process

Follow these systematic steps to accurately diagnose U0843. Each step builds on the previous one to ensure accurate diagnosis.

Step 1: Step 1: Perform an initial visual inspection of the BCM and associated wiring for visible damage, corrosion, or loose connections (5-10 minutes)

Step 1: Perform an initial visual inspection of the BCM and associated wiring for visible damage, corrosion, or loose connections (5-10 minutes).

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: Use a diagnostic tool like the GeekOBD APP to scan for all codes and retrieve freeze frame data to provide context for the U0843 code (10-15 minutes)

Step 2: Use a diagnostic tool like the GeekOBD APP to scan for all codes and retrieve freeze frame data to provide context for the U0843 code (10-15 minutes).

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: Conduct component testing with a multimeter to verify the integrity of the BCM and wiring harness (20-30 minutes)

Step 3: Conduct component testing with a multimeter to verify the integrity of the BCM and wiring harness (20-30 minutes).

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: After any repairs, recheck the system function to ensure the BCM operates correctly and clear the codes from the system (10-15 minutes)

Step 4: After any repairs, recheck the system function to ensure the BCM operates correctly and clear the codes from the system (10-15 minutes).

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 the vehicle under various conditions to confirm that the electrical systems are functioning as expected (15-20 minutes)

Step 5: Road test the vehicle under various conditions to confirm that the electrical systems are functioning as expected (15-20 minutes).

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 2012 Chevrolet Silverado

Vehicle: 2012 Chevrolet Silverado, 85,000 miles

Problem: Customer reported that the power locks and windows were not responding.

Diagnosis: Diagnostics revealed a U0843 code after checking with the GeekOBD APP. A visual inspection showed corroded connections at the BCM.

Solution: Replaced the BCM and repaired the wiring connections. Reprogrammed the new BCM to the vehicle.

Cost: $600, including parts and labor.

Result: All electrical functions restored, and customer reported no further issues.

Case Study 2: Wiring Repair on 2015 GMC Sierra

Vehicle: 2015 GMC Sierra, 50,000 miles

Problem: Customer experienced intermittent electrical failures in lights and locks.

Diagnosis: U0843 code was active. A thorough wiring inspection revealed frayed wires near the BCM.

Solution: Repaired the damaged wiring and secured connections. Conducted software updates.

Cost: $250 for repairs.

Result: Electrical systems functioned normally post-repair, and the customer was satisfied with the outcome.

Diagnose U0843

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: U0843
System: Network (Communication, CAN Bus)
Severity: MEDIUM
Category: Network Codes