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The error that shouldn't exist
The windshield wiper of an eight-year-old Renault Megane suddenly stopped working. Finding the defect became tricky after all known causes were checked and ruled out.
The error that shouldn't exist
Georg Ringseis thought the matter would be resolved quickly when a regular customer came to his workshop on Schwarzenbergplatz in Vienna with a defective windshield wiper. The Renault Megane, built in 2004, already had 116,000 kilometers on it, but was regularly serviced and well looked after. “The first snow had fallen that day. The fuse on the windshield wiper motor can blow due to overload,” says Ringseis. In fact, after replacing the fuse, the windshield wiper worked perfectly again, but three days later the customer came back with the same problem. Ringseis replaced the fuse again, but this time it blew again immediately after switching on the ignition. Conclusion: What was supposed to be a quick repair turned into a laborious detective search for clues with a surprising end result.
TROUBLESHOOTING CHRONOLOGY
- Diagnosegerät angeschlossen, Fehlerspeicher ausgelesen, Fazit: kein Fehlereintrag.
- Stecker vom Scheibenwischermotor abgezogen, Kurzschluss noch immer vorhanden. Vermutung: Das Zuleitungskabel könnte durchgescheuert sein.
- Kabelstrang freigelegt, doch keine defekte Stelle gefunden.
- Laut Anschlussplan vom Sicherungskasten Stecker vom Kabelstrang zum Wischermotor abgezogen. Fazit: Das Diagnosegerät zeigt einen Fehler im Lenksäulensteuermodul an.
- Aufwändiges Studium der Schaltpläne mit dem Ergebnis: Der Sicherungskasten enthält gleichzeitig das Steuermodul für die Motorraum-Elektronik. Der Wischermotor und die Lenksäulenelektronik hängen am gleichen Vielfachstecker – das erklärt den Fehlereintrag.
- Um das Problem weiter einzugrenzen, wird das Kabel vom Wischermotor abgezwickt – der Kurzschluss ist immer noch vorhanden.
- Nun kann der Fehler nur noch in der sogenannten „Zentralelektrik“ des Sicherungskastens liegen. Eine Sichtprüfung bringt allerdings kein Ergebnis, denn weder auf der Platine noch an den Steckern ist ein Defekt zu erkennen. Dennoch wird der Sicherungskasten ausgetauscht.
- Der neue Sicherungskasten wird eingebaut, alle Systeme werden auf Null zurückgesetzt. Fazit: Problem behoben, der Scheibenwischer funktioniert.
ERROR UNKNOWN
Both vehicle manufacturers and suppliers of diagnostic devices now operate comprehensive databases in which defects are documented in detail and processed for technical support. This means that not only brand workshops but also independent workshops receive valuable support in troubleshooting if necessary. However, it often happens that mysterious defects occur for the first time and perhaps only once, so that they do not appear in any error database. Georg Ringseis, owner of an independent workshop in Vienna, was unable to get any support from colleagues from a brand workshop because this particular error was unknown throughout the entire Renault organization. Even his research in relevant internet forums didn't help Ringseis, so he had no choice but to find out the cause himself. The problem was that repairing the windshield wiper motor took him almost an entire working day. “Of course I can’t possibly charge the customer for that,” says Ringseis. "It's important to maintain the right balance. I don't want to lose any regular customers."