B0779 - Transmission Control Module (TCM) Malfunction in Common Vehicles Like Honda Accord and Acura MDX

Quick Answer

B0779 means: B0779 indicates a malfunction in the Transmission Control Module (TCM), affecting transmission performance.

Fix: Check and replace faulty components Cost: $800 - $1200 Time: 90-180 minutes

Can I drive with B0779? Immediate attention is recommended to prevent further transmission damage.

Common Questions

What does B0779 mean and how does it affect my car?

The B0779 code signifies a malfunction in the Transmission Control Module (TCM), which regulates your vehicle's transmission functions. This can lead to issues like rough shifting or even transmission failure, affecting your car's performance and safety.

What are the most common causes of B0779 and how much does it cost to fix?

Common causes include a malfunctioning TCM, electrical issues, or low transmission fluid levels. Fixing a B0779 can range from $150 for wiring repairs to $1200 for TCM replacement, depending on the issue.

Can I drive my car with B0779 or should I stop immediately?

It is not safe to drive your vehicle with a B0779 code. Continuing to drive can lead to further transmission damage, potentially leaving you stranded and incurring higher repair costs.

How can I diagnose B0779 myself using GeekOBD APP?

Using the GeekOBD APP, you can scan for codes, check live data, and review freeze frame information to understand the conditions under which the B0779 code was triggered, assisting in pinpointing the issue.

What vehicles are most commonly affected by B0779?

The B0779 code is frequently seen in models like the 2013-2017 Honda Accord and 2014-2019 Acura MDX, among others. It’s essential to stay updated on recalls or Technical Service Bulletins (TSBs) related to your vehicle.

How can I prevent B0779 from happening again?

Regular transmission fluid changes, ensuring the electrical system is in good condition, and keeping up with software updates can help prevent the recurrence of the B0779 code.

What is B0779?

The diagnostic trouble code B0779 indicates a malfunction in the Transmission Control Module (TCM). This module is crucial for regulating various aspects of your vehicle's transmission system, such as gear shifting and performance optimization. When this code appears, it often means that the TCM has detected an issue that affects its operation or the overall performance of the transmission. Drivers may experience issues like erratic shifting, slipping gears, or even complete failure to engage the transmission. Notably, this code is common in vehicles such as the 2013-2017 Honda Accord and the 2014-2019 Acura MDX. Ignoring this issue can lead to more severe transmission problems, potentially resulting in costly repairs. It's advisable to address the B0779 code promptly to ensure your vehicle continues to operate smoothly and to avoid further damage to the transmission system. Regular maintenance and timely diagnostics can significantly enhance your vehicle's longevity and performance.

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

Symptoms

Common symptoms when B0779 is present:

  • The check engine light illuminates continuously, indicating an underlying issue that requires immediate diagnosis.
  • Drivers may notice harsh or erratic gear changes, often feeling like the vehicle is 'slipping' during acceleration, which can be alarming.
  • Fuel economy may decrease significantly, with reports of reduced efficiency by up to 15%, which can impact overall driving costs.
  • In some cases, the vehicle may unexpectedly stall or fail to engage into gear, leading to potential safety hazards on the road.
  • The dashboard may display additional warning lights related to the transmission or engine, signaling multiple issues that need to be explored.

Possible Causes

Most common causes of B0779 (ordered by frequency):

  1. A malfunctioning Transmission Control Module (TCM) is the most common cause, accounting for about 60% of all B0779-related issues. This can stem from software glitches or component failures.
  2. Electrical issues such as damaged wiring or poor connections can lead to TCM failures. This is often due to corrosion or wear, which can cause intermittent communication failures.
  3. Inadequate transmission fluid levels or contamination can also trigger the B0779 code. Regularly checking and maintaining fluid levels can prevent such issues.
  4. Less commonly, issues with the vehicle's onboard computer systems may interfere with TCM function, leading to erroneous codes and symptoms.
  5. Rarely, mechanical failures within the transmission itself can cause the TCM to misread operational parameters, which may require extensive repairs.

B0779 Repair Costs

Cost Breakdown by Repair Type

TCM Replacement

Replacing the faulty Transmission Control Module with a new or refurbished unit.

  • Total: $800 - $1200
  • Success rate: 90%
Wiring Repair

Repairing or replacing damaged wiring harnesses connected to the TCM.

  • Total: $150 - $400
  • Success rate: 80%
Software Update

Performing a software update on the TCM to correct any glitches.

  • Total: $100 - $300
  • Success rate: 70%
Money-Saving Tips for B0779
  • 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 B0779 Diagnosis Process

Follow these systematic steps to accurately diagnose B0779. Each step builds on the previous one to ensure accurate diagnosis.

Step 1: Step 1: Initial visual inspection - Begin with a thorough check for damaged wiring, loose connections, or signs of corrosion in electrical components (5-10 minutes)

Step 1: Initial visual inspection - Begin with a thorough check for damaged wiring, loose connections, or signs of corrosion in electrical components (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: OBD2 scan with GeekOBD APP - Use the GeekOBD APP to retrieve all diagnostic codes and review freeze frame data for context on the fault (10-15 minutes)

Step 2: OBD2 scan with GeekOBD APP - Use the GeekOBD APP to retrieve all diagnostic codes and review freeze frame data for context on the fault (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: Component testing - Perform tests using a multimeter or diagnostic tools to assess the TCM and related circuitry for faults (20-30 minutes)

Step 3: Component testing - Perform tests using a multimeter or diagnostic tools to assess the TCM and related circuitry for faults (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: System function test - After repairs, verify the operation of the transmission and clear any stored codes to ensure the issue is resolved (10-15 minutes)

Step 4: System function test - After repairs, verify the operation of the transmission and clear any stored codes to ensure the issue is resolved (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 verification - Conduct a road test under various conditions to confirm the repair's success and ensure transmission responsiveness (15-20 minutes)

Step 5: Road test verification - Conduct a road test under various conditions to confirm the repair's success and ensure transmission responsiveness (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: 2015 Honda Accord TCM Replacement

Vehicle: 2015 Honda Accord, 75,000 miles

Problem: The customer reported erratic shifting and the check engine light was on.

Diagnosis: After running diagnostics with the GeekOBD APP, the B0779 code was retrieved. A visual inspection revealed damaged wiring leading to the TCM.

Solution: Replaced the damaged wiring and updated the TCM software. A road test confirmed normal operation.

Cost: $950 (parts: $600 for wiring and $350 for labor)

Result: The vehicle operated smoothly post-repair, with improved shifting and no recurring codes.

Case Study 2: 2018 Acura MDX TCM Malfunction

Vehicle: 2018 Acura MDX, 50,000 miles

Problem: The vehicle would not shift into higher gears, causing significant power loss during acceleration.

Diagnosis: Diagnostic scans indicated a B0779 code. Component testing revealed a faulty TCM.

Solution: Replaced the TCM and performed a transmission fluid change.

Cost: $1,200 (parts: $900 for TCM and $300 for labor)

Result: Post-repair, the vehicle's shifting improved dramatically, and the customer reported excellent performance.

Diagnose B0779

Use GeekOBD APP for professional diagnosis!

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  • Step-by-step repair guidance
  • Professional-grade analysis
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Code Information

Code: B0779
System: Body (Airbags, Lighting, Security, Climate Control)
Severity: HIGH
Category: Body Codes