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Blazer Battery goes dead.

My 2001 Blazer will not start. New battery when running over 14 volts charging. But seems top drain the battery. if i disconnect the battery after use it is fine. I had a 94 Bravada did the same thing, the guy I purchased it from put a cut out switch right at the battery. But what a pain to open the hood after each use and flip the cutout. I see this is a common problem from all the posts but did not find a common solution.. help!


  • U need to find which circuit is drawing power when vehicle is shut off. Put an ammeter on battery and start pulling fuses.isolate which circuit/fuse causes amp draw to stop
  • If you've added any non-OEM electronics to the car, like audio or alarms, disconnecting them and seeing if it solves the problem is probably what I'd do first.

    Someone here mentioned an idea a while ago, a sort of short-cut method, to find which circuit these current draws are in, that didn't require the fuses to be pulled. Any circuit drawing power will cause the fuse to heat up a little. They said they used a laser-guided non-contact temperature probe and pointed it at the fuses one by one. I haven't done it, but it seems like it would work. This gadget, it sounds like it would cost $500, but actually here's one that is quite inexpensive, less than $40.

    Before using this method, you'd first want to measure the current at the battery to confirm you actually have a signficant phantom overall current draw. Anything over 100 mA when everything is off and sleeping would be suspicious. My Corolla, when I measured it, it had less than 10 mA with everything off.

  • I have heard many have had this problem so I wonder if it is coherent to this type vehicle?
  • @grego2 there is no one answer for every vehicle.

    Here are some examples of the sources of parasitic draw that I've encountered over the years.

    body control module
    instrument cluster
    ac pushbutton switch assembly
  • I purchased a a laser-guided non-contact temperature probe and will check it first chance i get.
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