Hi all,
Sorry in advance for the long post.
Have an A3 8PA 2010 CR140 here, it's been a good car for the last 35k miles but has had a few electrical problems throughout my ownership. Most have been easily fixable but this is a real nightmare issue.
It began with one day the car randomly shutting off at 50mph as if I'd just turned the key to the off position. All dials and screens died but radio stayed on. The car took a good few tries to start i.e. Taking out the key putting it back in and starting, but it did eventually start and got me home (about 5 miles). Critically, it had no fault codes at all. Excellent.
From then on, the car would shut off at completely random times. Sometimes it would go for days, sometimes 5 times in a 10 mile drive. At any speed, under any load, driving it however. I cannot consistently recreate the issue and nothing seems to influence it. 9 times out of 10 the car does not restart once it shuts off but does mostly turn over. However, 10 times out of 10, without fail, it starts as normal when I put a battery jumper on it. Voltage issue, has to be. Voltage seems fine when measured using multimeter (14.3-14.4V at idle, 12.6V when car is off) but due to the symptoms that was my first thought. The cars battery is around 6 months old and is the right battery for the car by VIN. In any case, I used the AA man's battery and that made no difference so it's not that.
Following that, I changed the alternator and solved the problem! For about 60 miles... same again. Changed the ignition switch didn't seem to make a difference. I then realized the dashcam was running off a Chinese power supply which was pulling power from the ignition/instrument cluster circuit. Knowing how sensitive the instrument clusters are in these cars, I thought that had to be the issue. Cheap power supply fault and running the circuit straight to ground, pulling enough voltage from the instrument cluster to shut the car off. Didn't cut out for nearly 3 weeks of driving after disconnecting the power supply and I was happy. Until yesterday, it shuts off again and I can't get more than 3 miles at a time before it shuts off again after being restarted with a battery booster
Fun drive home...
Now, I'm stuck. Out of ideas. Do any of you Audi boffins out there have any thoughts? It would be a real shame to scrap it over this issue as the engine is still sweet and I like the car.
My final thought is that it could be the instrument cluster. Send it away for testing/refurb? Waste of time? Would it certainly show a code if it was the instrument cluster? The lack of fault codes in a car that loves a good fault code is really throwing me off...
Sorry in advance for the long post.
Have an A3 8PA 2010 CR140 here, it's been a good car for the last 35k miles but has had a few electrical problems throughout my ownership. Most have been easily fixable but this is a real nightmare issue.
It began with one day the car randomly shutting off at 50mph as if I'd just turned the key to the off position. All dials and screens died but radio stayed on. The car took a good few tries to start i.e. Taking out the key putting it back in and starting, but it did eventually start and got me home (about 5 miles). Critically, it had no fault codes at all. Excellent.
From then on, the car would shut off at completely random times. Sometimes it would go for days, sometimes 5 times in a 10 mile drive. At any speed, under any load, driving it however. I cannot consistently recreate the issue and nothing seems to influence it. 9 times out of 10 the car does not restart once it shuts off but does mostly turn over. However, 10 times out of 10, without fail, it starts as normal when I put a battery jumper on it. Voltage issue, has to be. Voltage seems fine when measured using multimeter (14.3-14.4V at idle, 12.6V when car is off) but due to the symptoms that was my first thought. The cars battery is around 6 months old and is the right battery for the car by VIN. In any case, I used the AA man's battery and that made no difference so it's not that.
Following that, I changed the alternator and solved the problem! For about 60 miles... same again. Changed the ignition switch didn't seem to make a difference. I then realized the dashcam was running off a Chinese power supply which was pulling power from the ignition/instrument cluster circuit. Knowing how sensitive the instrument clusters are in these cars, I thought that had to be the issue. Cheap power supply fault and running the circuit straight to ground, pulling enough voltage from the instrument cluster to shut the car off. Didn't cut out for nearly 3 weeks of driving after disconnecting the power supply and I was happy. Until yesterday, it shuts off again and I can't get more than 3 miles at a time before it shuts off again after being restarted with a battery booster
Fun drive home...Now, I'm stuck. Out of ideas. Do any of you Audi boffins out there have any thoughts? It would be a real shame to scrap it over this issue as the engine is still sweet and I like the car.
My final thought is that it could be the instrument cluster. Send it away for testing/refurb? Waste of time? Would it certainly show a code if it was the instrument cluster? The lack of fault codes in a car that loves a good fault code is really throwing me off...
