Battery, Alternator, or Starter?
08-03-2012, 02:42 PM
#11
AudiWorld Super User
If someone determined a 40 A current draw and you dont hear a motor on or humming (example seat adjustment switch stuck and a motor cutting in & out because of a thermal protector or the radiator fans running; Try this: Remove bottom cover from engine. Charge battery by driving/idling/ external charger. Park car in garage for evening. Set an alarm clock etc. After four hours or more when the engine is cold, put your hand on the Bosch alternator. You will find it toasty warm and your battery drained. Common failure mode.
As an option, just hook up a battery charger so your battery is not drained. Next morning everything except the battery should be stone cold. Your alternator won't be. Now, I have had it intermittent. Some mornings all was well, others completely dead battery. New battery made no difference so imagine how happy I was when it was discharged. That's when I tried the charger trick. 2nd morning toasty warm alternator. I replaced it. Typical symptom of a leaky, but not fully shorted diode.
One other thing, The MMI battery level indicator is not the most accurate thing, I hardly every look at it. More of a curiousity thing.
As an option, just hook up a battery charger so your battery is not drained. Next morning everything except the battery should be stone cold. Your alternator won't be. Now, I have had it intermittent. Some mornings all was well, others completely dead battery. New battery made no difference so imagine how happy I was when it was discharged. That's when I tried the charger trick. 2nd morning toasty warm alternator. I replaced it. Typical symptom of a leaky, but not fully shorted diode.
One other thing, The MMI battery level indicator is not the most accurate thing, I hardly every look at it. More of a curiousity thing.
08-03-2012, 07:34 PM
#12
AudiWorld Senior Member
Join Date: Dec 2011
Posts: 714
Likes: 0
Received 0 Likes
on
0 Posts
Good advice all....
Thanks. Wouldn't want my baby (and dem sick rims..) torched in the morning....
K9
K9
If someone determined a 40 A current draw and you dont hear a motor on or humming (example seat adjustment switch stuck and a motor cutting in & out because of a thermal protector or the radiator fans running; Try this: Remove bottom cover from engine. Charge battery by driving/idling/ external charger. Park car in garage for evening. Set an alarm clock etc. After four hours or more when the engine is cold, put your hand on the Bosch alternator. You will find it toasty warm and your battery drained. Common failure mode.
As an option, just hook up a battery charger so your battery is not drained. Next morning everything except the battery should be stone cold. Your alternator won't be. Now, I have had it intermittent. Some mornings all was well, others completely dead battery. New battery made no difference so imagine how happy I was when it was discharged. That's when I tried the charger trick. 2nd morning toasty warm alternator. I replaced it. Typical symptom of a leaky, but not fully shorted diode.
One other thing, The MMI battery level indicator is not the most accurate thing, I hardly every look at it. More of a curiousity thing.
As an option, just hook up a battery charger so your battery is not drained. Next morning everything except the battery should be stone cold. Your alternator won't be. Now, I have had it intermittent. Some mornings all was well, others completely dead battery. New battery made no difference so imagine how happy I was when it was discharged. That's when I tried the charger trick. 2nd morning toasty warm alternator. I replaced it. Typical symptom of a leaky, but not fully shorted diode.
One other thing, The MMI battery level indicator is not the most accurate thing, I hardly every look at it. More of a curiousity thing.
08-04-2012, 01:12 PM
#13
Audiworld Junior Member
Thread Starter
Join Date: Feb 2012
Posts: 30
Likes: 0
Received 0 Likes
on
0 Posts
I removed the fuse for the dension gateway 500. It was plugged into the auxiliary radiator fuse (slot 38). Don't know if that means anything since I don't know if the aux radiator runs since it doesn't have a proper fuse. I'll let it be for a couple hours and continue on to another suggestion if that doesn't work.
As far as removing the bottom cover from the engine....I don't know how. I'm not really a car guy beyond the minor stuff that everybody should know how to do. I also don't have a garage; it's parked in my driveway.
As far as removing the bottom cover from the engine....I don't know how. I'm not really a car guy beyond the minor stuff that everybody should know how to do. I also don't have a garage; it's parked in my driveway.
08-04-2012, 04:07 PM
#14
AudiWorld Super User
Six large 1/2 turn aluminum screw bolts and two plastic ones in each front wheel well. You should be able to remove them by placing the car in lift mode if you are not physically too big. Otherwise you'll be paying someone to troubleshoot. Maybe you have a mechanically inclined neighbor or friend that can help. I say it is the alternator since I have had a few Bosch ones fail this way. Also note that the alternator "idiot light" which is supposed to illuminate with ignition on but motor not running will usually not illuminate when you have this problem . Not many individuals catch this. Good luck.
Thread
Thread Starter
Forum
Replies
Last Post
doublesin
A8 / S8 (D3 Platform) Discussion
6
01-25-2014 07:12 AM
ltooz_a6_a8_q7
A4 Cabriolet (B6 Platform) Discussion
1
12-10-2011 07:15 AM
