Alternator charging system

Tiny
LHERKO
  • MEMBER
  • 1998 CHEVROLET ASTRO
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 142,000 MILES
My van would not start yesterday, after running two days earlier. The battery seemed low. I took the battery out, ant it tested OK. I took the alternator out, and it tested as a bad diode. I installed a rebuilt alternator. But, the charging system is not working properly, I ran the battery down while driving today. What should I look at next?
Wednesday, October 1st, 2008 AT 2:27 PM

4 Replies

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Did you check gauges fuse no.4 10amp and also have the battery load tested to check its condition-if it fails the load test replace it


https://www.2carpros.com/forum/automotive_pictures/12900_cewd_1.jpg



https://www.2carpros.com/articles/how-to-check-a-car-alternator

Load test the rebuilt alternator-an alternator if its good should be putting out between 13.5 to 15.5 volts with a high load being use such as heater/lights/AC
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Wednesday, October 1st, 2008 AT 5:11 PM
Tiny
LHERKO
  • MEMBER
  • 8 POSTS
Rasmataz, thanks for your continued replies! I do not measure any dymanic voltage from the alternator at the battery, only the static 12v or less, regardless if the van is running or not. I have good ground between the battery and the alternator. The wiring diagram you posted shows a fusible link between the battery and the alternator. Could this be the culprit? If so, how difficult is it to locate on my van?
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Thursday, October 2nd, 2008 AT 10:46 AM
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
If you measure the reading there at the alternator battery terminal it should read the battery voltage -if not the fuse link is open
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Thursday, October 2nd, 2008 AT 10:49 AM
Tiny
LHERKO
  • MEMBER
  • 8 POSTS
Rasmataz, continuity and voltage to the battery side of the alternator kept reading OK. So I pulled the new alternator out and had it tested, it was OK. So I looked at the wiring a little closer. The small wire, on the alternator, that goes to the gauge on the dash felt suspicious at the alternator connector. I spliced it back together, reinstalled the alternator, and everything seems to be working OK!
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Friday, October 3rd, 2008 AT 7:02 PM

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