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GM Techs... again... 97 Chevy with a BAD parasitic draw, 90A+

Discussion in 'The Garage' started by sled_dog, Oct 26, 2006.

  1. sled_dog

    sled_dog 1 ton status

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    What seems like out of nowhere my truck has developed a terrible parasitic draw. It will drain the batter to the point that it won't start the truck in a matter of minutes. Hooked up my Digital Multimeter. Which popped the fuse instantly. Dad's old Analog Ammeter pegs the gauge at 90 Amps(at least it seems to say 90). I mean it literally makes a noise when it hits the other side it pegs so hard. I disconnected th starter wire(just replaced the starter) and it didn't make a difference. Pulled the power wire to the underhood fusebox, same situation. I'm thinking I am going to chase my tail looking for a short to ground, but all systems work and no fuses are popping. I don't get it. Voltage drop across any of the battery cables are .01 at the most. Any thoughts on a direction to go here? I checked voltage drop from the battery positive terminal on the starter(with the wire hooked up of course) to the engine block. It was full voltage(at the time only 8 pitiful volts). But when I disconnected the positive cable from the starter, and tested for continuity between the starter terminal and the case, I have an open loop(as it should be with the solenoid disengaged). Its one of those confusing wiring nightmares, or obvious things....
     
  2. sled_dog

    sled_dog 1 ton status

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    doh just realized I haven't even bothered trying to test continuity between the battery positive terminal and ground.... duh most basic check for short to ground.
     
  3. Bigg R

    Bigg R Registered Member

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    Check the AC compressor or relay!!!
     
  4. 84blazend

    84blazend Registered Member

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    I am in college for automotive technology, and we recently had a car (ford taurus) come in with a problem just like yours.

    First, take the positive battery cable off of the battery. Put your multimeter leads on the battery post (+), and the other on the battery cable. It should be really high. Then...This sounds stupid but.... unplug your alternator. Put your multimeter leads between the battery post and the battery cable again. Does it still show a huge power draw?

    If you don't get a voltage draw thats huge this time, I would replace the alternator. We replaced it on the taurus, and that did the trick.

    I'm not saying this is the problem, but that is where I would start.
     
  5. sled_dog

    sled_dog 1 ton status

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    yeah I looked at the alternator, I removed the feedback wire from it, but didn't mess with the power connector. I will do that in the morning. I give up for tonight. My luck it is that obvious an item.

    I remved every fuse and relay on the truck, didn't go away with any of them. So it is something not fed through a fuse.
     
  6. 84blazend

    84blazend Registered Member

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    You need to remove the power wire from the alternator
     

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