Updating control unit software in VAG vehicles can sometimes lead to unexpected fault codes. This article examines a specific case involving a software update in a 5F control unit using VCDS and the resulting “1552 – Expanded Bus Activity Active” fault alongside the common “1555 – checking software version management” error, often related to Vcds Svm (Software Version Management). We’ll explore the process used to resolve the SVM issue and delve into potential causes of the persistent expanded bus activity fault.
Understanding VCDS SVM and Control Unit Updates
VCDS (Vag-Com Diagnostic System) is a powerful diagnostic tool used for Volkswagen, Audi, Seat, and Skoda vehicles. When updating control unit software, VCDS sometimes triggers a “1555” fault code, indicating an issue with SVM. This often requires specific procedures within VCDS to correct the software version information stored in the control unit. While this is a known issue, the relationship between software updates and the “1552 – Expanded Bus Activity Active” fault is less clear.
Case Study: 5F Control Unit Update and Resulting Faults
In this particular instance, a 5F control unit (Information Electronics) was updated from train “MHI2_ER_AUG22_P4212” (version 1177) to “MHI2_ER_AUG22_P5092” (version 1329) using the red (engineer) menu within the MMI (Multi Media Interface). As expected, the update initially triggered the “1555” fault code related to VCDS SVM. Applying the standard HEX procedures successfully cleared this error. However, a new fault code, “1552 – Expanded Bus Activity Active,” appeared and persisted even after clearing fault codes.
Addressing the “1555 – Checking Software Version Management” Fault (VCDS SVM)
The “1555” fault, common after control unit updates via the engineer menu, signifies a mismatch in the recorded software version. This requires manual correction using VCDS’s adaptation channels to align the actual software version with the control unit’s stored information. This process typically involves entering specific hexadecimal values to update the SVM data.
Investigating the “1552 – Expanded Bus Activity Active” Fault
The “1552” fault suggests an unusual level of communication on the vehicle’s CAN (Controller Area Network) bus. This could be caused by several factors, including:
- Faulty Control Unit: While less likely after a successful software update, a hardware issue within the updated control unit could be causing excessive communication.
- Wiring Issues: Damaged or poorly connected wiring within the CAN bus system can lead to communication errors and trigger the “1552” fault.
- Software Compatibility: Although the update seemingly installed correctly, there might be underlying incompatibilities between the new software and other modules on the CAN bus.
- Coding Issues: Incorrect coding within the 5F control unit or related modules could contribute to the increased bus activity.
Troubleshooting Steps and Further Analysis
Further diagnostic steps are required to pinpoint the root cause of the “1552” fault. These might include:
- Checking for Other Fault Codes: Scanning all control units for related fault codes could provide additional clues.
- Monitoring CAN Bus Traffic: Using VCDS or other specialized tools to monitor CAN bus traffic could reveal which modules are contributing to the increased activity.
- Reviewing Wiring Diagrams: Carefully inspecting the wiring diagrams for the affected modules and the CAN bus system can help identify potential wiring problems.
- Consulting Technical Service Bulletins (TSBs): Checking for TSBs related to the “1552” fault or the specific control unit update could offer solutions or insights.
Conclusion
While successfully resolving the VCDS SVM-related “1555” fault is relatively straightforward, the persistent “1552 – Expanded Bus Activity Active” fault requires a more in-depth investigation. Systematic troubleshooting, utilizing the suggested steps, is crucial to identify the underlying cause and implement the appropriate solution. This case highlights the importance of thorough diagnostics and the complexities that can arise even after seemingly successful software updates in modern vehicles.
