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Traced Parasitic Draw to Z3 Antenna Unit?

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    Traced Parasitic Draw to Z3 Antenna Unit?

    Car is an '89 325is.

    Been dealing with a bad parasitic draw for years and because I don't daily the car, I've basically put up with it. About a year ago, I attempted to fix the issue and my troubleshooting led me to the SI batteries. Replaced them and the issue improved. Initially I thought I had solved it completely but eventually realized the problem still existed to a lesser extent.

    Tonight I dug into it again and found an 80 mA draw placing the meter in series with the negative battery cable. Pulling fuses led me to fuse 28 which dropped the current to 38mA. My understanding is that 30 to 40mA is the correct range for these cars.

    Bentley says fuse 28 is for the lighter and power antenna. Years back I swapped out the original dead power antenna for a lightweight, simple Z3 amplified unit. The Z3 unit only has one terminal I believe, whereas the factory E30 harness has two wires, red and white, leading to the power antenna. I've had just one of those wires (don't remember which sitting here on the couch) hooked up to the Z3 unit.

    Regardless, as soon as I unplugged the antenna, the draw dropped to 38mA so I pinpointed the issue as the antenna.

    This surprises me. Is this a known issue? Do I have it hooked up incorrectly? What could have failed in the antenna to cause this draw?

    Thanks.
    '89 BMW 325is Zinnoberrot / '88 VW Jetta GLI 16v Tornado Red / '89 VW Jetta GLI 16v Tornado Red / '89 VW GTI 16v Bright Blue Metallic / '91 BMW 325i Black / '91 BMW 325i Sport Black / '92 VW GTI 16v Black / '92 VW GTI 16v Montana Green / '01 Audi A4 Avant TQM Silver Metallic / '01 VW Jetta GLX VR6 Black

    #2
    The red wire on the e30 harness is constant power. If you used that, the antenna would be powered all the time, causing your draw. The white wire is only powered when the radio is on. Use that one instead.

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      #3
      Originally posted by AndrewBird View Post
      The red wire on the e30 harness is constant power. If you used that, the antenna would be powered all the time, causing your draw. The white wire is only powered when the radio is on. Use that one instead.
      You're exactly right, good point! I just confirmed it with a meter. Don't I feel dumb, all these years of trouble because I made a bad assumption.
      '89 BMW 325is Zinnoberrot / '88 VW Jetta GLI 16v Tornado Red / '89 VW Jetta GLI 16v Tornado Red / '89 VW GTI 16v Bright Blue Metallic / '91 BMW 325i Black / '91 BMW 325i Sport Black / '92 VW GTI 16v Black / '92 VW GTI 16v Montana Green / '01 Audi A4 Avant TQM Silver Metallic / '01 VW Jetta GLX VR6 Black

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