U0676 - Communication Issue with the Transmission Control Module in 2015-2018 Jeep Cherokee and Dodge Dart

Quick Answer

U0676 means: DTC U0676 indicates a communication error between the Engine Control Module and the Transmission Control Module.

Fix: Check and replace faulty components Cost: $150 - $400 Time: 90-180 minutes

Can I drive with U0676? Immediate attention is recommended to prevent further damage to the transmission.

Common Questions

What does U0676 mean and how does it affect my car?

DTC U0676 indicates that your car's Engine Control Module and Transmission Control Module are having communication issues. This can lead to problems like erratic shifting, stalling, or even reduced fuel efficiency. Over time, ignoring this issue can cause more serious damage to your transmission, ultimately affecting your car's performance and safety.

What are the most common causes of U0676 and how much does it cost to fix?

Common causes of U0676 include faulty wiring or connectors, software glitches in the ECM or TCM, and defective modules themselves. Repair costs can vary significantly; simple wiring repairs may cost around $150, while replacing a module can run upwards of $1500. Regular diagnostics and software updates can help prevent these issues from arising.

Can I drive my car with U0676 or should I stop immediately?

Driving with a U0676 code is not advisable. While you may be able to drive short distances, the vehicle may enter limp mode, severely limiting performance and risking further damage to the transmission. It's best to address this issue as soon as possible.

How can I diagnose U0676 myself using GeekOBD APP?

To diagnose U0676 using the GeekOBD APP, first connect the app to your vehicle's OBD2 port. Use the app to retrieve any stored codes and review freeze frame data. This will give you context on when the issue occurs. Follow through with the diagnostic steps outlined, focusing on the wiring and modules involved.

What vehicles are most commonly affected by U0676?

U0676 commonly affects models like the 2015-2018 Jeep Cherokee and Dodge Dart. These vehicles have been reported to experience this code due to communication issues between the ECM and TCM. It's advisable to check for recalls or technical service bulletins (TSBs) related to this code.

How can I prevent U0676 from happening again?

To prevent a recurrence of U0676, ensure regular vehicle maintenance, including inspections of wiring and connectors, and keep your software up to date. Additionally, avoid aftermarket modifications that could interfere with the vehicle's electrical systems.

What is U0676?

The diagnostic trouble code (DTC) U0676 indicates a communication malfunction between the Engine Control Module (ECM) and the Transmission Control Module (TCM). This issue arises when the ECM fails to receive or interpret information from the TCM properly. In simpler terms, your car's computer systems are not 'talking' to each other as they should. This can lead to various issues, including erratic shifting, decreased fuel efficiency, and in some cases, the vehicle may enter 'limp mode' to protect the engine and transmission from further damage. Common symptoms include the illumination of the check engine light, unusual transmission behavior, and potential stalling during gear changes. For car owners, this means that if you experience these symptoms, it’s crucial to address the problem promptly to avoid further complications. Many vehicles, especially models from Jeep and Dodge produced between 2015 and 2018, are known to encounter this code. Regular maintenance and software updates can help mitigate these issues, but if you find yourself facing DTC U0676, a thorough diagnostic approach is essential to pinpoint the exact cause and apply the right fix.

System: U - Network (Communication, CAN Bus)

Symptoms

Common symptoms when U0676 is present:

  • Check engine light illuminates and remains on until the issue is resolved.
  • Transmission may hesitate or shift roughly, causing a jarring experience during acceleration.
  • Fuel economy drops significantly, often by 10-15%, as the transmission struggles to operate efficiently.
  • Vehicle may enter limp mode, limiting speed and power to prevent further damage.
  • Unusual noises from the transmission area may be heard, indicating internal issues.

Possible Causes

Most common causes of U0676 (ordered by frequency):

  1. Faulty wiring or connectors between the ECM and TCM (60% likelihood). Regularly inspect and clean connections to prevent corrosion.
  2. Software glitches or outdated firmware in the ECM or TCM (25% likelihood). Keeping your vehicle's software updated can help mitigate this issue.
  3. Defective ECM or TCM itself (10% likelihood). If both the wiring and software check out, further testing may be needed to assess the modules.
  4. Electrical shorts or grounding issues (3% likelihood). Ensure all electrical connections are secure and functioning.
  5. A rare instance of external interference from aftermarket devices (2% likelihood). If modifications have been made, consider reverting to original equipment.

U0676 Repair Costs

Cost Breakdown by Repair Type

Wiring Repair

Repairing or replacing damaged wiring and connectors between ECM and TCM.

  • Total: $150 - $400
  • Success rate: 90%
ECM/TCM Software Update

Updating the software of the ECM or TCM to the latest version.

  • Total: $100 - $200
  • Success rate: 80%
Module Replacement

Replacing a faulty ECM or TCM if they are deemed defective.

  • Total: $800 - $1500
  • Success rate: 95%
Money-Saving Tips for U0676
  • 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 U0676 Diagnosis Process

Follow these systematic steps to accurately diagnose U0676. 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).

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).

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 or specific diagnostic tools to test suspected components like connectors and wiring (20-30 minutes)

Step 3: Component testing - Use a multimeter or specific diagnostic tools to test suspected components like connectors and wiring (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 - Verify proper operation after repairs and clear codes (10-15 minutes)

Step 4: System function test - Verify proper operation after repairs and clear codes (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 - Drive the vehicle under various conditions to confirm repair success, ensuring no codes reappear (15-20 minutes)

Step 5: Road test verification - Drive the vehicle under various conditions to confirm repair success, ensuring no codes reappear (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: Transmission Communication Repair on 2016 Jeep Cherokee

Vehicle: 2016 Jeep Cherokee, 55,000 miles

Problem: Customer reported check engine light was on, and the vehicle hesitated during shifting.

Diagnosis: Initial diagnostic revealed the U0676 code. A visual inspection showed corroded connectors at the TCM.

Solution: Replaced corroded connectors and updated the TCM software. Conducted a road test to ensure repairs were successful.

Cost: $250 (parts: $50, labor: $200)

Result: The vehicle performed normally post-repair, and the check engine light remained off.

Case Study 2: ECM Replacement on 2017 Dodge Dart

Vehicle: 2017 Dodge Dart, 45,000 miles

Problem: Customer experienced rough shifting and check engine light; U0676 code was present.

Diagnosis: All wiring was intact, but the ECM was found to be faulty after thorough testing.

Solution: Replaced the ECM with a new module and performed a software update. Road tested the vehicle.

Cost: $1200 (parts: $1000, labor: $200)

Result: The vehicle's shifting issues were resolved, and performance returned to normal.

Diagnose U0676

Use GeekOBD APP for professional diagnosis!

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Code Information

Code: U0676
System: Network (Communication, CAN Bus)
Severity: HIGH
Category: Network Codes