VW Tiguan Electrical Issues: Beyond Dead Battery Fix

I had a very similar issue with my 2018 VW Golf, and as someone with moderate experience working on cars, I can share what happened. The symptoms matched yours exactly, weak starts, flickering lights, and unusual electrical glitches. The charging system was showing clear signs of trouble. Initially, I suspected the alternator, but after a proper diagnosis at my workshop, they found the battery terminals were corroded and the battery itself was heavily discharged beyond recovery. The low voltage was causing all sorts of electrical gremlins. The workshop performed a full charging system test, which confirmed the alternator and power supply were actually fine. The main culprit was the battery, it had degraded to the point where it could no longer hold a proper charge. The repair included: Complete battery replacement, Cleaning and securing battery terminals, Full charging system diagnostic, Computer system reset Total cost came to 290€ and the car has been running perfectly since then. Before suggesting specific solutions for your case, could you share: How old is your current battery? Have you noticed any corrosion around the battery terminals? Does the alternator warning light come on while driving? What voltage reading do you get while the engine is running? This information would help determine if your issue matches what I experienced or points to a different charging system problem.

Last service was just completed at 88441km and included a full inspection of charging components. After testing and investigation, my issue turned out to be more complex than a basic battery fault. The main battery showed good voltage readings when tested individually, but a voltage drop test revealed significant resistance in the ground cable connection to the chassis. The workshop found the battery ground strap had deteriorated, creating inconsistent electrical flow through the charging system. They also discovered corroded connections at the fuse box, which contributed to the voltage fluctuations. The complete repair included: Replacement of main ground cable, Cleaning and securing all major electrical connections, Testing of charging system components, Computer system reset Total repair cost was 180€ and resolved all electrical problems completely. Regular voltage readings now show proper charging system operation at both idle and running speeds.

Thanks for sharing those details about your ground cable repair. The voltage regulator and other charging system components being good matches what I found during my troubleshooting too. My Golf actually had very similar symptoms, but the root cause was slightly different. While you had a bad ground strap, my electrical problem stemmed from corroded battery terminals and a failing power supply connection at the main fuse box. After getting tired of the unusual electrical gremlins, I had the entire charging system inspected. Like your case, the alternator and battery tested fine independently. The workshop discovered the real issue was deteriorated connections causing resistance in the circuit. My repair included cleaning all battery terminal connections and replacing a damaged power distribution block. The total came to around 220€ and completely resolved the flickering lights and starting issues. These cases show why proper electrical system maintenance is so critical. Even with a good battery and alternator, bad connections in the charging system can cause all sorts of strange symptoms. Would recommend having the workshop do a thorough voltage drop test across all major power connections at your next service. This often catches developing issues before they cause problems.

Thanks everyone for the helpful charging system insights. Just wanted to close this thread with a quick update since others might benefit from my experience. The voltage regulator and battery voltage both tested normal, but the failing ground strap was causing major charging system problems. The inconsistent ground connection made the power supply unstable, leading to all those frustrating electrical issues. Key findings from my repair: Main battery had good voltage but ground cable was severely corroded, Damaged connections at fuse box worsened the voltage problems, New ground strap and cleaned terminals fixed everything, Total repair cost 180€ Been several weeks now with perfect electrical system operation. The unusual failures and flickering lights are completely gone. Battery terminal voltage stays steady and the car starts strong every time. Important lesson learned, deteriorated ground connections can mimic a bad battery or alternator. Getting a proper charging system diagnosis saved me from unnecessarily replacing good components. Thanks again for helping me understand these electrical gremlins. Hope this helps others track down similar charging system problems in their vehicles.