The Audi A3’s interior lighting system can sometimes present challenges. This article addresses two common problems: an unusual current draw in the interior lighting circuit and a door sensor malfunction. We’ll delve into possible causes, diagnostic steps, and potential solutions.
Current Draw on Interior Lighting Circuit
A persistent 100mA current draw on the interior lighting circuit, even when all lights are off, can drain the battery and lead to starting problems. While a slight current draw is normal for certain modules, 100mA is excessive. This issue could stem from a faulty component, a short circuit, or an issue with the onboard supply control unit (J519).
Possible Causes and Diagnosis
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Faulty Components: Despite visually inspecting the interior lights and confirming they are in working order, a faulty bulb, switch, or wiring connection could still be the culprit.
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Short Circuit: A short to ground in the power supply wire or earth wires shorted to positive are potential causes of the excessive current draw. Refer to the wiring diagram for the interior lighting circuit (available on forums like Ross-Tech) to identify and test these wires for continuity and resistance. The 1V reading at the glove compartment and front interior lights with fuse 15 removed suggests a possible voltage leak, warranting further investigation into the J519 control unit and its associated wiring.
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J519 Control Unit: The onboard supply control unit (J519) manages the power distribution to various vehicle systems, including interior lighting. A malfunction within this unit might be responsible for the persistent current draw. Further diagnostics using a VAG-COM scanner can help pinpoint issues with the J519.
Door Sensor Malfunction
The second issue involves the door electronics, specifically the inability of the J519 to detect an open door. The central locking system functions correctly, suggesting the problem lies in the door contact switch within the door lock mechanism.
Diagnosis and Solution
- Microswitch in Door Lock: The most likely cause is a faulty microswitch in the door lock. This switch signals the J519 when the door is open or closed. To access and test this switch, removing the door trim panel is necessary. A multimeter can be used to check the switch’s continuity in both open and closed door positions.
Auto-Scan Fault Codes Analysis
The provided auto-scan reveals several fault codes, some directly related to the issues described:
- Address 09 – Central Electrics (J519): While no codes directly relate to the current draw, investigating the J519 further is recommended given the suspicious voltage readings.
- Address 52 – Door Elect, Pass: The codes
00929(Locking Module for Central Locking; Front Passenger Side – Implausible Signal) and00106(Signal Central Locking SAVE/LOCK Passenger Side – Implausible Signal) directly indicate a problem with the passenger door locking module, correlating with the door sensor issue.
Conclusion
Troubleshooting electrical issues in an Audi A3 requires a systematic approach. By understanding the potential causes, utilizing diagnostic tools like a VAG-COM scanner and a multimeter, and referencing wiring diagrams, you can effectively isolate and resolve problems with the interior lighting circuit and door sensors. Remember to consult reputable resources like Ross-Tech forums for detailed wiring diagrams and diagnostic procedures specific to your Audi A3 model.
