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I tried the tradition "pull fuses one at a time" method and still can't find the short.

People from other forums have said that the engine block being hot may be symptomatic of a bad ground cable -- but this doesn't make sense to me.

So basically, symptoms are:

1) Parasitic Draw at > 0.2 amp. (Not sure of the exact number -- waiting for another multimeter as mine won't give a reading at the 10A setting)

2) Engine block at 12 Volts -- so about .5/.6 voltage drop between positive terminal and frame/block.

3) Car will not start / no indicator lights, etc. (Usb accessories seem to work, however.)

4) None of the fuses will stop the parasitic draw

What do I do next? Thanks!

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  • Hello, and welcome to Stack Exchange. Are you measuring the engine block against the ground strap/car body? If so, then that's really surprising; there's no way the engine is insulated from the body. Mar 22, 2018 at 23:08
  • Thanks, glad to be here! No, I'm measuring it against the negative terminal on the battery (12V) and the positive terminal (-.5 volts). That still feels very unexpected to me?
    – q335r49
    Mar 22, 2018 at 23:40
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    DVOMs measure the difference between the com lead and the volt lead. So if you have ~12v on the volt lead and ~0v on the com lead than the difference would be ~12v. Try running a wire from the engine to the b- terminal and see if it corrects the reading. A 500mV voltage drop on a wire suggests either a load on the circuit or resistance in the circuit. Even with the engine running you should expect to see a very small < 100mV drop on the b+ or - cables. If the engine truly is the source of the draw try disconnecting the alternator as a shorted regulator can cause draw.
    – Ben
    Mar 23, 2018 at 0:43
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    Also, edit your post so that it contains an actual question. Even if its something simple like, what do i do next?
    – Ben
    Mar 23, 2018 at 0:49
  • Try disconnecting every wire on the starter and measure again.
    – SteveRacer
    Mar 23, 2018 at 8:55

1 Answer 1

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  1. With the negative terminal detached and the positive terminal attached, measuring a ~12V drop from the unattached negative terminal to the engine block with negative lead at the terminal and positive lead at the block is expected behavior as the multi-meter completes the circuit and acts as a large resistor across which there is a voltage drop.

  2. Parasitic draw of ~ .2 A was is also expected behavior.

  3. In my case, I experienced a sudden loss of electronic power steering while driving; after parking, the car refused to start. It turned out to be a bad / burned connection from one of the bolted on wires leading from the positive terminal. Unbolting and cleaning the connection fixed the problem.

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