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Motion Sensor Driving Me Nuts

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    If you prove that the on-star RF is the cause of the spurious motion detected events, then perhaps the following can help.

    Go to
    and note the schematic of the Hawkeye (an older version).

    This schematic is to modify the device - ignore all of that.
    See R6 in the schematic - near the IR sensor.
    I'd try putting a small capacitor across (in parallel with) R6. To bypass RF to ground but not disrupt the much lower frequency signal from the IR sensor. The capacitor might be .001 microfarad. Or .01 microfarad. These are half the diameter of a penny. Soldering skill required.

    If there are no spurious dusk/dawn messages, we assume that the RF is not getting into the circuit at TR2.


      Thanks for all the replies. Although I don't know it's onstar for a fact, I've resolved myself to this and created a workaround for it.

      I now have a device (C1) for the car that triggers when the motion sensor in the car has been on for three minutes. This indicates that the car is on the road and I set the device status and last change time accordingly.

      If C1 is "on" and motion is detected by the sensor, it indicates that I'm home and parked. An off signal from the sensor confirms this. The "parked" script resides as CAC in the doomotion device.

      Seems to work for me although I'd prefer not having the issue with onstar. Again, thanks for the help.
      Regards, Bob


        I have thought about putting one of those X10 motion sensors in the car, with an event for ignition on/off. Could be easy:
        Using the the Hawkeye mod web page info...
        Disconnect the standard photocell for light/dark.
        Run a wire to some circuit in the car which is 12V when the ignition is on. Maybe poke a wire under a fuse clip in the fuse holder.
        Run that, and ground, to the Hawkeye. May need a resistor to bring the 12V down to 3 V or so.

        Should get a ignition on and off events. That would help the occupancy detection algorithms.


          Or you could use a DS10, connect the wires to a 12v relay that can be wired to your switched fuse block.