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Need Help-B5 down for 2nd week, won't charge!

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2nd charge down for helpb5 need week wont
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1.3K views 2 replies 2 participants last post by  zmaninco  
M
#1 ·
Ok, this is now driving me crazy. :banghead: My 99 1.8T 60K miles has been down for like 2 weeks and no one can figure it out:

  1. About 2 weeks ago, car wouldn't start, had to boost to start it.
  2. Checked charging system, indicated alternator needed replacement
  3. While hooking up another battery (instead of my regular), heard a pop and saw smoke come out of alternator, smelt like burnt electrical
  4. Sent alternator to shop, found all diodes blown and they replaced
  5. Re-installed alt and still found lower than 12V when vehicle running
  6. Replaced battery
  7. Removed alt and returned to shop. They bench tested and found 14.7V, 110A (mine is a 90A Valeo), and their test light goes out when voltage passes battery voltage. Brushes are good/clean.
  8. Checked both leads on alternator with ignition on and I have 12V on both the blue wire and the lead.
  9. Checked continuity from battery + to alternator lead and no resistance between them.
  10. Checked all fuses, they are ok. (Even the one's under the dash and that crazy one waaay to the left)
  11. Radio does not work as well. Don't even get a SAFE prompt.
  12. My connector under the drivers floor is like new.
  13. Battery symbol is lit up in dash. (Goes out when I remove the Blue wire from the alt).
  14. Brought car to an Auto Electrical Shop and after racking their brain for 4 days, they returned the car and said they didn't know and thought it was "The Dash". They didn't charge me anything.
Any ideas? What about the rectifier? Is it possible that the alternator still benches good and won't give me the current with a bad rectifier? How can I check this? The guy at the Auto Electric Place mentioned that he thought the alternator wasn't being "activated".

Any other thoughts and ideas before I list my 99 1.8T in the Marketplace Forum?:confused:

-Mitch
99 Passat 1.8T
04 XC70 AWD
69 Triumph GT6+
 
Z
#3 ·
Voltage regulator is internal and would be checked as part of the alternator check. If the shop is getting 14.7V on a bench test, the alt should be good. Check the output on the car, it should be about the same - around 14.7V. If you have that output at the alt, you are losing it somewhere along the way to the battery.

Since the alt light is on on the dash, my guess is you are not getting enough juice out of the alt. I would look to replace it.
 
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