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Charging problems

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by dutterback, Dec 16, 2000.

  1. dutterback

    dutterback Registered Member

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    My 87 k-5 wouldnt hardly turn over. Since the battery was a few years old I changed it. Then the gauge showed a discharge. I then changed the alternator with a new one and now it still wont charge. If I charge the battery and let it run with lights on etc.. it eventualy drains down to where it wont start again. I figure either my alternator is not charging or something is draining the battery before it can. please help with any suggestions on what to do next. Thanks. Sorry for the long post
     
  2. mudhog

    mudhog THEGAME Staff Member Super Moderator

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    have you tried putting new battery cables on?

    s.smith 77blazer lookin 4 mud
     
  3. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Ok did you recently mess with the starter? the routing of the alternator is from alternator to starter (same terminal battery does to) to battery. Check that wire for damage or corrosion down at the starter. If the battery cables were bad it wouldn't start so you can rule that out. Also that wire plugged into the top of the alternator is a Feild wire. It excites the alternator to get it to start charging. I believe there is a Fuse in the Fuse box that is for that wire marked "alt". If the old alternator shorted out and blew that fuse your new alternator would not work.

    Diging it in the dirt with my K5's
    Grim-Reaper
    http://grimsk5s.coloradok5.com/
     
  4. OFFRDK5

    OFFRDK5 1/2 ton status Premium Member

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    Did you happen to check your belt tension? If that belt isn't on there good you will run them down rather quickly. Look on the underside of the belt for glazing...then tighten the belt.

    SK-15
    J**P...it's whats for dinner!
    http://SK-15.coloradok5.com
     
  5. dutterback

    dutterback Registered Member

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    The belt tension is fine. I checked and cleaned my battery cables, they seamed o.k. I havent messed with the starter at all. Could it be that ive got something (wire) in the wrong place? Is it possible that my sarter went bad? I will check the fuse and see if it's o.k. Thanks a bunch.
     
  6. dutterback

    dutterback Registered Member

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    I dont find a "alt" fuse in my fuse box. Also my alternator wire runs form the alternator to the battery and then splits off to the starter with a larger wire. There is no fuse link between the altornater and the battery, so shouldn't it be charging? Help please.
     
  7. Hobbes68

    Hobbes68 Registered Member

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    I'd check the wire from the alt to the battery with a meter to see if it's got a lot of resistance (indicating corrosion or other damage). If so, you need to replace it. Also make sure you have power going to one of the two skinny wires in the plug on top of the alt. It'll still work without them (If memory serves correctly) but it won't charge as much at low RPM's. Check the voltage at the battery with the engine runnning. It should be approx. 14 volts. If so, the alternator is charging. If this is the case, remove the battery cables and check for corrosion. Since you say it starts ok, this isn't likely to be your problem, but check it anyway. Sometimes on side terminal batteries corrosion occurs around the bolt and under the rubber cable end so it's not readily visible from the outside. Clean it out with warm water and baking soda. What else???? Make sure your ground is in good condition also. If you check everything out and still can't find the cause of the problem, bring the alt to the place you bought it and have them bench test it to make sure it's working. Sometimes a defect gets through quality control. If they won't or can't bench test it they should be happy to replace it.

    By any chance, does your truck have an external voltage regulator on it? It wouldn't be stock from GM, but someone may have put one in at some point for some unknown reason. It may be defective or in need of adjustment. If so, that would be the first place I'd check (There are very few people I trust to do the job right!). Look for a small box about the size of a pack of cigarettes with wires that go to the alternator. Ford regulators are typically used whenever an exteranal regulator is called for. If you have one, you can open it up and adjust the output voltage to about 14.0 to 14.5 volts. Any more than that will fry your battery and cause it to boil over.

    Another thing that just came to mind. Do you have a volt meter or ammeter in the guage cluster? Does it appear to be working properly? All the time? A shorted/defective guage could be sending a signal (or preventing a signal) to the computer (and then to the alt) causing a no charge condition. I had a similar problem in a TPI Camaro I used to own. It took me forever to finally figure that one out.

    Good luck!
     
  8. dutterback

    dutterback Registered Member

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    Thanks hobbes68. I checked the wire from the alt to battery and found a place where someone had spliced on a wire for power. It didnt look that great so I replaced the plug (.75 cents) The alternator is now showing a good charge and doesnt drain. Guess I didnt need a battery or alternator, but what the heck. Thanks again.
     

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