5399 Mercedes Fault Code: Expert Diagnosis & Solutions

The 5399 Mercedes Fault Code indicates an implausible CAN signal related to the ‘Gear selected’ from the Electronic Transmission Control (ETC/EGS) module to the Electronic Stability Program (ESP). Understanding this fault code requires specialized knowledge, and AutoExplain.com is here to provide expert remote support for efficient troubleshooting and solutions.

1. Understanding the 5399 Mercedes Fault Code

The 5399 Mercedes fault code signals a communication breakdown between the transmission control unit (ETC/EGS) and the electronic stability program (ESP) regarding the selected gear. This fault, typical in models like the 2006 Benz ML350, can lead to performance issues and safety concerns. It’s essential to accurately diagnose the problem to ensure the proper functioning of these critical systems.

1.1. What Does the 5399 Code Mean?

The 5399 code specifically points to the ESP receiving an incorrect or inconsistent signal about the gear selection from the ETC/EGS module. This discrepancy can trigger the ESP to react inappropriately, potentially affecting vehicle stability and safety systems.

1.2. Systems Affected by the 5399 Fault Code

• Electronic Stability Program (ESP): This system relies on accurate information to maintain vehicle stability, particularly during challenging driving conditions.
• Electronic Transmission Control (ETC/EGS): The transmission control unit manages gear selection and communicates this information to other vehicle systems.
• Controller Area Network (CAN): The CAN bus is the communication network that allows various modules to exchange data, including gear selection.

1.3. Common Symptoms Associated with the 5399 Code

• ESP Warning Light: The ESP warning light may illuminate on the dashboard.
• Limp Mode: The vehicle may enter limp mode, limiting engine power and speed.
• Erratic Shifting: Transmission shifting may become irregular or unpredictable.
• Reduced Stability Control: The effectiveness of the ESP system may be compromised.
• Other Warning Lights: Depending on the severity, other warning lights related to the transmission or stability control may appear.

2. Potential Causes of the 5399 Mercedes Fault Code

Several factors can contribute to the appearance of the 5399 fault code. A thorough investigation is necessary to pinpoint the exact cause.

2.1. CAN Bus Communication Issues

• Faulty Wiring: Damaged or corroded wiring in the CAN bus can disrupt communication between the ETC/EGS and ESP modules.
• Loose Connections: Poorly connected or loose connectors can cause intermittent signal loss.
• Wiring Harness Damage: Physical damage to the wiring harness can interrupt CAN bus communication.

2.2. ETC/EGS Module Problems

• Software Glitches: Software errors or corrupted data within the ETC/EGS module can lead to incorrect gear selection signals.
• Module Failure: A malfunctioning ETC/EGS module may not accurately detect or transmit gear selection information.
• Sensor Malfunctions: Internal sensors within the ETC/EGS module, such as speed sensors, may fail, causing incorrect data.

2.3. ESP Module Issues

• Software Problems: Software errors in the ESP module can misinterpret the gear selection signal.
• Module Failure: A faulty ESP module may not properly process or react to the gear selection information.

2.4. Sensor-Related Problems

• Wheel Speed Sensors: Inaccurate readings from wheel speed sensors can affect the ESP’s ability to correctly interpret gear selection data, leading to fault code 5399.

3. Diagnostic Steps for the 5399 Mercedes Fault Code

Diagnosing the 5399 fault code requires a systematic approach to identify the root cause. Here’s a step-by-step guide for technicians:

3.1. Initial Scan and Code Verification

Use a professional-grade scan tool, such as the Autel MaxiDiag Elite MD802, to read and record all stored fault codes.

Note: Ensure the scan tool is compatible with Mercedes-Benz vehicles and can access the ESP and ETC/EGS modules.

3.2. Visual Inspection

• Wiring and Connectors: Carefully inspect the wiring and connectors related to the ESP and ETC/EGS modules for signs of damage, corrosion, or looseness. Pay particular attention to the CAN bus wiring.
• Ground Connections: Check the ground connections for both modules to ensure they are clean and secure.

3.3. CAN Bus Testing

• CAN Bus Voltage: Use a multimeter or oscilloscope to check the CAN bus voltage levels. Look for any abnormalities or fluctuations.
• Signal Integrity: Verify the integrity of the CAN bus signals using an oscilloscope. Ensure the signals are within the specified range and free from noise or interference.

3.4. ETC/EGS Module Testing

• Software Update: Check for any available software updates for the ETC/EGS module. Outdated software can sometimes cause communication issues.
• Live Data: Monitor live data from the ETC/EGS module using the scan tool. Verify that the gear selection signal is accurate and consistent.
• Sensor Readings: Check the readings from internal sensors within the ETC/EGS module, such as speed sensors, to ensure they are within the specified range.

3.5. ESP Module Testing

• Software Update: Check for any available software updates for the ESP module.
• Live Data: Monitor live data from the ESP module to verify that it is receiving the correct gear selection signal from the ETC/EGS module.
• Actuator Tests: Perform actuator tests using the scan tool to check the functionality of the ESP system components.

3.6. Wheel Speed Sensor Testing

• Sensor Readings: Use the scan tool to check the readings from all wheel speed sensors. Compare the readings to ensure they are consistent and accurate.
• Sensor Functionality: Test the functionality of each wheel speed sensor by monitoring the signal output while the vehicle is in motion.

4. Repair Procedures for the 5399 Mercedes Fault Code

The repair procedure will depend on the specific cause identified during the diagnostic process.

4.1. CAN Bus Repair

• Wiring Repair: Repair or replace any damaged or corroded wiring in the CAN bus. Ensure all connections are secure and properly insulated.
• Connector Replacement: Replace any faulty connectors that are causing intermittent signal loss.
• Wiring Harness Replacement: If the wiring harness is severely damaged, replace it with a new one.

4.2. ETC/EGS Module Repair

• Software Update: Update the ETC/EGS module software to the latest version.
• Module Replacement: If the ETC/EGS module is faulty, replace it with a new or refurbished unit. Ensure the replacement module is properly programmed and coded to the vehicle.

4.3. ESP Module Repair

• Software Update: Update the ESP module software to the latest version.
• Module Replacement: If the ESP module is faulty, replace it with a new or refurbished unit. Ensure the replacement module is properly programmed and coded to the vehicle.

4.4. Sensor Replacement

• Wheel Speed Sensors: Replace any faulty wheel speed sensors with new, OEM-quality sensors.

5. Advanced Troubleshooting Tips

Consider these advanced troubleshooting tips if the initial repair attempts do not resolve the 5399 fault code:

5.1. Check for Related Fault Codes

Review all stored fault codes to identify any related issues that may be contributing to the 5399 code. Addressing these related codes may help resolve the communication problem between the ETC/EGS and ESP modules.

5.2. Perform a Thorough System Reset

After completing the repairs, perform a thorough system reset using the scan tool. This can help clear any residual data and ensure that all modules are communicating correctly.

5.3. Consult Mercedes-Benz Technical Resources

Refer to Mercedes-Benz technical service bulletins (TSBs) and diagnostic procedures for additional guidance. These resources may provide specific troubleshooting steps or repair recommendations for the 5399 fault code.

5.4. Data Logging and Analysis

Use the scan tool to log data from the ESP and ETC/EGS modules while the vehicle is in operation. Analyze the data to identify any anomalies or inconsistencies in the gear selection signal.

6. The Role of AutoExplain.com in Resolving Complex Faults

AutoExplain.com offers expert remote support to assist technicians in diagnosing and resolving complex fault codes like the 5399 Mercedes-Benz code. Our team of experienced automotive engineers provides real-time guidance and support to help you efficiently troubleshoot and repair vehicle systems.

6.1. Remote Diagnostic Assistance

AutoExplain.com can remotely access your scan tool data and provide expert analysis of the fault codes and live data. Our engineers can help you interpret the data and identify the root cause of the problem.

6.2. Step-by-Step Repair Guidance

We provide step-by-step repair guidance, including detailed instructions, wiring diagrams, and component locations, to help you perform the necessary repairs efficiently.

6.3. Software Programming and Coding

AutoExplain.com offers remote software programming and coding services for Mercedes-Benz vehicles. We can help you update module software, program new modules, and perform necessary coding to ensure proper system functionality.

6.4. Access to Technical Resources

We provide access to a comprehensive database of technical resources, including service manuals, wiring diagrams, and technical service bulletins, to help you stay informed and up-to-date on the latest repair procedures.

6.5. Real-Time Support via WhatsApp and Email

Our team is available to provide real-time support via WhatsApp and email. You can contact us with any questions or concerns you may have during the diagnostic and repair process.

7. Preventive Measures to Avoid the 5399 Fault Code

Preventive maintenance can help reduce the likelihood of encountering the 5399 fault code and other communication-related issues.

7.1. Regular Maintenance of Electrical Connections

Periodically inspect and clean electrical connections to ensure they are free from corrosion and properly secured. Apply dielectric grease to connectors to prevent moisture intrusion and corrosion.

7.2. Proper Wiring Harness Management

Ensure that wiring harnesses are properly routed and secured to prevent chafing or damage. Use protective sleeves or conduit to protect wiring from harsh environmental conditions.

7.3. Software Updates

Keep the software in your vehicle’s modules up-to-date by performing regular updates. Software updates often include bug fixes and performance improvements that can help prevent communication issues.

7.4. Professional Diagnostic Scans

Schedule regular diagnostic scans with a professional scan tool to identify and address any potential issues before they escalate into major problems.

8. Case Studies: Resolving the 5399 Mercedes Fault Code

Here are a few case studies illustrating how the 5399 fault code can be resolved in different scenarios:

8.1. Case Study 1: CAN Bus Wiring Issue

A technician encountered the 5399 fault code on a Mercedes-Benz C-Class. After performing a thorough diagnostic scan, they found several other communication-related fault codes. A visual inspection revealed damaged wiring in the CAN bus harness. The technician repaired the damaged wiring and secured the connections. After clearing the fault codes and performing a system reset, the 5399 code did not return.

8.2. Case Study 2: ETC/EGS Module Software Glitch

Another technician faced the 5399 fault code on a Mercedes-Benz E-Class. The diagnostic scan showed no obvious wiring or sensor issues. After consulting with AutoExplain.com, the technician decided to update the ETC/EGS module software. The software update resolved the communication issue, and the 5399 fault code was cleared.

8.3. Case Study 3: Faulty Wheel Speed Sensor

In a third case, a technician found the 5399 fault code on a Mercedes-Benz ML350. Along with the 5399 code, there were also fault codes related to the wheel speed sensors. The technician tested the wheel speed sensors and found that one of them was faulty. Replacing the faulty wheel speed sensor resolved the issue, and the 5399 fault code was cleared.

9. Understanding Mercedes-Benz Diagnostic Tools

Mercedes-Benz vehicles require specialized diagnostic tools to accurately diagnose and repair complex issues. Here are some of the commonly used tools:

9.1. Mercedes-Benz XENTRY/DAS

XENTRY/DAS (Diagnostic Assistance System) is the official diagnostic software used by Mercedes-Benz dealerships and authorized service centers. It provides comprehensive diagnostic capabilities, including fault code reading, live data monitoring, component testing, and software programming.

9.2. Autel MaxiSys Elite

The Autel MaxiSys Elite is a professional-grade diagnostic tool that offers extensive coverage for Mercedes-Benz vehicles. It supports advanced functions such as ECU programming, coding, and adaptations.

9.3. iCarsoft MB II

The iCarsoft MB II is a handheld diagnostic tool designed specifically for Mercedes-Benz vehicles. It offers basic diagnostic functions such as fault code reading and clearing, live data monitoring, and component testing.

9.4. Foxwell NT530

The Foxwell NT530 is another popular diagnostic tool for Mercedes-Benz vehicles. It supports a wide range of diagnostic functions and offers user-friendly interface.

10. Frequently Asked Questions (FAQ) about the 5399 Mercedes Fault Code

10.1. What does the 5399 fault code mean on a Mercedes-Benz?

The 5399 fault code indicates an implausible CAN signal related to the ‘Gear selected’ from the Electronic Transmission Control (ETC/EGS) module to the Electronic Stability Program (ESP).

10.2. What are the common symptoms associated with the 5399 code?

Common symptoms include the ESP warning light, limp mode, erratic shifting, and reduced stability control.

10.3. What are the potential causes of the 5399 fault code?

Potential causes include CAN bus communication issues, ETC/EGS module problems, ESP module issues, and sensor-related problems.

10.4. How do I diagnose the 5399 fault code?

The diagnostic process involves an initial scan, visual inspection, CAN bus testing, ETC/EGS module testing, ESP module testing, and wheel speed sensor testing.

10.5. Can I fix the 5399 fault code myself?

While some repairs can be performed by experienced DIYers, complex issues often require professional diagnostic tools and expertise. AutoExplain.com offers remote support to assist technicians in resolving these complex fault codes.

10.6. What is the role of AutoExplain.com in resolving the 5399 fault code?

AutoExplain.com provides expert remote support, including diagnostic assistance, step-by-step repair guidance, software programming and coding, access to technical resources, and real-time support via WhatsApp and email.

10.7. How can I prevent the 5399 fault code?

Preventive measures include regular maintenance of electrical connections, proper wiring harness management, software updates, and professional diagnostic scans.

10.8. What diagnostic tools are commonly used for Mercedes-Benz vehicles?

Commonly used tools include Mercedes-Benz XENTRY/DAS, Autel MaxiSys Elite, iCarsoft MB II, and Foxwell NT530.

10.9. Is it necessary to update the software in the ETC/EGS and ESP modules?

Yes, software updates often include bug fixes and performance improvements that can help prevent communication issues and resolve the 5399 fault code.

10.10. What should I do if the 5399 fault code persists after completing the repairs?

If the fault code persists, double-check all connections, perform a thorough system reset, consult Mercedes-Benz technical resources, and consider data logging and analysis to identify any remaining issues.

11. Contact AutoExplain.com for Expert Assistance

Don’t let the 5399 Mercedes fault code slow you down. Contact AutoExplain.com for expert remote support and get your vehicle back on the road quickly and efficiently. Our team of experienced automotive engineers is ready to assist you with all your diagnostic and repair needs. Reach out to us via:

• Office Address: 4590 Angus Road, New York, United States
• WhatsApp: (+84)967469410
• Email: [email protected]
• Website: AutoExplain.com

At AutoExplain.com, we understand the challenges technicians face when dealing with complex fault codes. Our goal is to provide you with the knowledge, tools, and support you need to efficiently diagnose and repair vehicle systems. Contact us today and experience the difference expert remote support can make.

If you’re wrestling with the 5399 Mercedes fault code or any other complex automotive issue, don’t hesitate to reach out to AutoExplain.com. We’re here to provide you with swift, expert assistance. Contact us via WhatsApp at (+84)967469410 or email us at [email protected] for immediate support. Let AutoExplain.com be your trusted partner in automotive diagnostics and repair, ensuring your vehicle’s electronic stability program and transmission systems are functioning flawlessly.

12. Key Programming Services by AutoExplain.com

In addition to diagnostic and repair assistance, AutoExplain.com also offers key programming services for Mercedes-Benz vehicles. If you need a new key programmed or a lost key replaced, our expert technicians can provide remote key programming services to get you back on the road quickly.

12.1. Benefits of Remote Key Programming

• Convenience: Remote key programming eliminates the need to visit a dealership or locksmith, saving you time and hassle.
• Cost-Effectiveness: Our remote key programming services are often more affordable than traditional methods.
• Expert Assistance: Our experienced technicians ensure that your new key is properly programmed and coded to your vehicle.