A common issue for Volkswagen owners is the persistent appearance of a license plate light warning on the dashboard, even after replacing the bulb. This problem is often accompanied by the 01504 fault code in VCDS (Vag-Com Diagnostic System), indicating a defective bulb. This article explores the causes and solutions for this frustrating issue, specifically focusing on the 01504 Vcds error code.
Understanding VCDS Error Code 01504
The 01504 error code specifically points to a problem with the license plate light bulb (X). The code often includes additional information such as “014 – Defective – Intermittent,” suggesting the fault may not be constant. Even with new bulbs installed and visually confirmed as working, the error persists and cannot be cleared using VCDS. This indicates a problem beyond a simple bulb failure.
Common Causes of Error 01504
While a burnt-out bulb is the most obvious cause, the persistence of the 01504 code after replacement points to other potential issues:
- Wiring Issues: Damaged or corroded wiring in the license plate light circuit is a frequent culprit. This can include broken wires, loose connections, or damaged connectors.
- Grounding Problems: A poor ground connection can prevent the circuit from completing, triggering the fault code. The ground wire or its connection point may be corroded or loose.
- Bulb Holder Corrosion: Corrosion within the bulb holder can disrupt the electrical contact, leading to the error.
- Faulty BCM: In rare cases, a malfunctioning Body Control Module (BCM) can incorrectly report the 01504 error, even with a functioning license plate light circuit.
Diagnosing and Fixing Error 01504
Resolving the 01504 error requires a systematic approach to diagnose the underlying problem:
- Visual Inspection: Carefully examine the wiring harness, connectors, and bulb holders for any visible damage, corrosion, or loose connections.
- Voltage Check: Use a multimeter to verify that the correct voltage is reaching the bulb holder. This will help determine if a wiring or grounding problem exists.
- Grounding Check: Test the ground connection for continuity using a multimeter. Ensure a solid connection between the ground wire and the chassis.
- Bulb Holder Cleaning: Clean the bulb holder contacts with a contact cleaner or fine sandpaper to remove any corrosion.
- Wiring Repair/Replacement: If damaged wiring is found, repair or replace the affected section.
- BCM Check: If all other checks are clear, consider having the BCM diagnosed by a qualified technician. This is a less common cause but should be considered if other solutions fail.
alt text: Close up of a car mechanic's hands working on car wiring
Conclusion
The 01504 VCDS error code, indicating a license plate light issue, can be a persistent problem even after replacing the bulb. By systematically checking the wiring, grounding, bulb holder, and potentially the BCM, you can pinpoint the root cause and effectively resolve the issue. If the problem persists after these checks, consulting a qualified automotive technician is recommended.
