This Bug was on a local errand when it suddenly jerked a couple times then drove fine. On her way back from her destination it just died. It would turn over but not start and everything they could check looked fine. They towed it to their regular maintenance shop where they informed her it needed a computer as they couldn’t even pull codes to get a starting point. Unfortunately they didn’t have the ability to perform that type of a repair so it would need to go to the dealer or another shop. She was calling around looking for a non dealer option and was referred to me by one of those shops as one of the local experts on German cars. When she got in touch with me, I explained it’s most likely not what they thought as VW computers are pretty tough and rarely fail. After going over her options, she decided to tow it to us for a proper diagnosis to determine if it in fact needed a computer, and if so, to make certain what exactly killed the old one. There is nothing more sad than to see smoke rolling out from a brand new computer.
To digress a bit, that brings back memories from my military days when I was working on one of the Warthogs Radar Jammers (A-10’s). A guy that was working with us burnt up not one $40,000 power supply but two and if my memory serves me, was in the process of ordering a third before being pulled aside. The powers to be vehemently explained to him the importance of properly trouble shooting electrical failures. His “Shot Gun” method of just throwing parts at the problem hoping for a fix was not a method they were willing to fund. The discussion was memorable to say the least. To this day I can remember watching the smoke roll out a hole in the side of the case every time he went to power it up and him saying “wow, another bad power supply”.
Back to the Bug problem, we began with pulling codes to verify the other shops findings and sure enough there was no communication. A bit of interesting information was we couldn’t access the transmission computer either. Could we have two bad computers??? That would be rare, but most likely just another clue. We found fuse 10 was blown and when we installed another, it would hold for a bit then blow again. We installed our short finder and dove into the factory (not so user friendly) track wiring diagrams and proceeded to trace out all that fuse powered. We found it was the main power to a relay that also powered the engine control computer and interestingly enough, the ignition coil and ignition module assembly. We accessed the coil and unplugged it and just like that the fuse stopped blowing. When we tested the coil for current draw we verified it was our problem. Once we got the new fuse in and working, we were able to access the computer where we found many codes, some related to our coil problem and some to the power loss issue.
We found out the coil and wires were replaced about 20,000 miles ago and you could tell it was a lower quality aftermarket unit. We replace the coil assembly and the ignition wires with quality German made parts and all is working well. The moral of this story, don’t throw parts at a problem without performing the correct test procedures. And secondly make sure your German car is serviced by someone that knows German cars. Not saying your current shop is unqualified but German cars are very different. If your shop doesn’t understand all the little idiosyncrasies even a simple oil change done with questionable quality parts, can leave you whishing you had gone with a more experienced option.