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96 2dr S-10 blazer erratic alt charging ??

Discussion in 'Chevy Trucks' started by scholzee, Jan 13, 2003.

  1. scholzee

    scholzee Senior Member
    Messages: 243

    I just bought truck 96 S-10 blazer 6'6" western plow. The guy said truck died on highway AAA towed it said it needs Alt, he was tired of it so sold it to me. The battery was stone dead would not charge, I put in a new battery the alt. looks new and has a remanufactured date of 8/20/02 on it. Some times it charges at 14.5 volts and other times it is down at 12 volts. I verified the dash guage by using a Digital volt meter on the battery and I get the same results, the lights also dim when its not charging. I took the alt to Autozone and Advanced Auto parts they both bench test it and say its good. I cleaned all ground and power connections at engine block and battery, mounting bracket etc. Serp Belt and tensioner look good. there is only one brown wire going to the voltage reg part of alt and it has .5 volt less than battery voltage at it with key on (11.5 volt when batt at 12v). The output of alt has one cable to battery and then 2 wires to fusable links, no voltage drop across fusable link so I think they are good. Any replies on trouble shooting appreciated.
  2. Big Nate's Plowing

    Big Nate's Plowing PlowSite.com Addict
    Messages: 1,266

    bad ground or coroded quick disconnects, did you use die electric grease?;)

  3. scholzee

    scholzee Senior Member
    Messages: 243

    The connector going to the voltage regulator has one wire and there is dielectric grease on it, I even removed the female pin and recrimped it to get a firmer connection on the male pin. the output connections on alt do not have grease, but stud and nuts look like new and are tight. Battery connections, ground to header panel, ground to frame ,ground to engine block have all been cleaned and tightened. Alt mounting bracket was removed and cleaned. I have .19 ohm between alt case and neg lead of battery, fusable links are firm and no voltage drop across them. I am out of ideas.
  4. icebladez

    icebladez Member
    from sask
    Messages: 74

    Hi scholzee..my '95 went thru problems similar on the blazer after the alt showing it was good,for me it was the starter..the solenoid was robbing power ,and to compound the complexity,i had the misfourtune of having to go thru two brand new faulty starters form Canadian tire..No more flirts with thinking 'cheap parts for me'!!
    Last edited: Oct 4, 2005
  5. scholzee

    scholzee Senior Member
    Messages: 243

    Wow thanks for the tip !! but that thread was from 2 1/2 years ago. I still have the truck and love it. It turned out to be a bum alternator, must have been something internal, new alt and all was fine. I usually post fixes to my threads I guess I missed that one. Thanks anyhow !!
  6. MickiRig1

    MickiRig1 PlowSite Veteran
    Messages: 3,617

    I know this is old but this might help someone.
    I had the same problem with my F-250.
    I took the alternator apart and found the leads from the internal voltage regulator were corroded and one was broken. It would charge as long as the ends touched. And of course when it was tested it would charge like a champ!
    It drove me nuts for a full week.