1981 parasitic drain

Discussion in 'Troubleshooting & Diagnosis' started by 7.62fmj, May 17, 2017.

  1. 7.62fmj

    7.62fmj Veteran Member

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    So my battery has been discharging (yes, I read the tracing a drain sticky). Yesterday I had a little time to play with the multimeter and got the following readings:
    12.35V with ignition off
    14.55V idling
    14.7-14.9V under throttle
    13.9V idling under load (headlights only)
    26.9 AC idling
    12.9 when ignition turned off, dropped down to 12.56

    At 10pm I disconnected the alternator because I thought a diode might be bad
    reading 12.4V

    Next morning @ 930am (11.5 hours later) battery was down to 12.26V

    Reconnected the alt and checked the draw (193ma-194ma). Checked the fuses and the tail lamp circuit dropped to 13ma when I pulled the fuse.

    I don't know much about electronics and I find wiring diagrams confusing. So my question is what all runs off that circuit and can I trace it down without tearing apart my interior?
     
  2. Rdobbs1977

    Rdobbs1977 Huge Guns N Roses Fan

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    I'm a little confused as to whether or not you have a draw prob going on....You're volt numbers seem good to me. Usually people have a draw problem when they find their battery is dead for no reason. By your statements above, you have not performed a draw test. Were it me and had the need I'd do the following:

    1. Grab a test light
    2. disconnect the neg bat cable
    3. hook the clip of test light to the cable and touch the prob to neg terminal
    4. if the light lights up then you've got a draw
    5. if that's the case, any wires hooked to your battery or junction block, remove them one by one, each time testing with the test light. if the light goes out in removing one of these wires, you've found the circuit. if the light never went out, then start popping fuses one by one.
     
  3. 7.62fmj

    7.62fmj Veteran Member

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    I did a draw test and read 193milliamps. Disconnected fuses and when I pulled the fuse in the tail lamp slot it dropped to 13.
    My readings were good because I had been driving the day before. The battery discharges within several days if I do not drive or charge.
     
  4. Gary S

    Gary S Administrator Lifetime Gold Member

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    These wiring diagrams
    http://www.nastyz28.com/camaro/diagram.html
    indicate that the tail lamp fuse supplies power to the tail lamps, side markers, and license plate light on the rear and the park lights and side markers on the front of the car. It might also power other devices that I didn't see. You may have to spend some time tracing the wires on the diagram.
     
  5. 7.62fmj

    7.62fmj Veteran Member

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    I noticed my license plate light doesn't come on so that's probably a good place to start looking. If it is the light, I would need to trace the wire from the light forward? And thanks for the diagram, I did find one online, but it was not as clear of a picture.
     
  6. 7.62fmj

    7.62fmj Veteran Member

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    None of the bulbs in the back affect the amount of drain, but if I unplug the harness in the trunk the drain drops about 20 ma. But somewhere between there and the battery there's still almost 200 ma of drain. Took out the interior panels and I don't see any obvious grounding or rubbed through insulation or anything. Ideas?
     
  7. 7.62fmj

    7.62fmj Veteran Member

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    Forgot to check gauges
     
  8. hogg

    hogg Veteran Member

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    shut you glove box door maybe , have that happen to me
     
  9. 7.62fmj

    7.62fmj Veteran Member

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    I have no glovebox light. Also as far as I can tell that's on a different circuit than what's pulling juice
     
  10. Twisted_Metal

    Twisted_Metal Administrator Staff Member Lifetime Gold Member

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    With the lights off.... Rotate the headlight knob to different positions (dash light dimmer) to see if it changes the draw.
    I'm not exactly sure what that would tell you but it's an easy test as there should be no draw until the dome light goes on.
     

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