Bumping an old thread for a similar problem
Vehicle is a 2007 Audi A3, 2.0T (BPY) with DSG trans, 180k miles. Electrically and mechanically identical to a GTI for all intents and purposes.
I am well-versed with electrical, but have not had to deal with a no-start condition quite like this before. To add to that, all of my tools are two hours away at work.
For several months the car would occasionally hesitate to start, acted like the battery was weak, taking two or three tries to crank. I currently have a cheapy Walmart battery, and it was only really happening if the car sat for more than a day, so I didn't think much of it. The day this no-start issue began, it did the same thing when I first started it in the morning. Drove 20 minutes before shutting it off, figured it had time to charge. Same hesitation when I started it back up five minutes later, drove another 10 minutes and parked. Tried to start it again after 5-10 minutes and it hesitated once, tried to start it again and it wouldn't even try to turn over. I've tried several times since and it still doesn't attempt to crank, nor do the dash lights dim like when the starter is drawing current. No check engine, immobilizer, or other fault lights coming on in the cluster.
I have pulled the starter and it does spin up when voltage is applied. When it was in the car I metered it and it does have constant 12v on the large 4 gauge power wire going to the starter, however I was not getting anything on the smaller trigger wire going to the solenoid while turning the key to start. I have tested every relay in the fuse box under the hood as well as under the dash to the left of the steering column, all are good (or at least they click when manually applying voltage and ground to 85 and 86.) I have 12v on the ignition wire going to the BCM with the key in at the run position, and have tried manually applying 12v to the starter wire going to the BCM while turning the key to the start position. I have also tried applying 12v to the smaller wire at the solenoid to see if the starter would turn.
Not sure if it's related, but about a month ago the key was very hard to turn from 'off' to 'run,' like to the point that I was afraid something was going to break. Once it did turn though it worked fine, and would occasionally happen but 90% of the time turned normally with no resistance. I chalked it up to unusually cold weather and figured I'd check it out when I had time. It is not doing that now, nor was it happening the day that the car began refusing to start.
My first thought before testing anything was that something gave out in the ignition switch/cylinder, but I spoke with a friend who is a tech at an Audi dealer and he said he has never seen an ignition switch go bad, and that when they stick like that some graphite will fix it. Based on the symptoms, he suspected the starter is bad or the engine is seized (this was prior to pulling the starter and testing it out of the car.) My thoughts are that if the engine were seized the starter would still try to turn and the lights would dim as it draws current, which is not happening. I suspect there is some electrical fault further up the chain, especially since the solenoid wire is not being energized when turning the key. I have not yet tried turning the engine by hand as I am lacking the correct tool here. On top of that, I took my meter back to work and forgot it, so I'm about to run out and go buy one.
dleej30- I'm not sure what ended up being the solution to your problem. Was it a fuse or relay for the ECU? Anyone have any other suggestions? Thanks!
P.S. Further info- Battery is charged and I've also tried starting it with a jump pack connected. Tried two different keys as well. The cluster display indicates that it is in park, and I have moved the shifter out of park and back a few times. Won't start in neutral either, just though I didn't expect it to. The car is APR tuned and has been since it was under a year old, flashed through the OBD port. I don't have access to my Vag-com cable at this time either, unfortunately.