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Constant power draw on cargo light?

Discussion in 'Gen 4 Prius Accessories and Modifications' started by Frogerelli, Apr 26, 2020.

  1. Frogerelli

    Frogerelli Junior Member

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    Hey, I am working on replacing the weak cargo light with some strip LEDs on either side of the cargo area. With the hatch closed and putting a voltmeter into the wiring connector shows a power draw of 1.09 volts. With the hatch open it shows 11.94 volts.

    Does anyone know why it isn't 0 volts with the hatch closed?
     
    #1 Frogerelli, Apr 26, 2020
  2. alanclarkeau

    alanclarkeau Senior Member

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    All that I can think is that the ECU is connected - to detect if the light is ON. There is a timer, I think 20 minutes, where it turns some bulbs off. Only a guess.

    @Elektroingenieur might be able to help?
     
    #2 alanclarkeau, Apr 26, 2020
  3. The Professor

    The Professor Senior Member

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    Just tested my light in the boot, unplugged it, and put meter into the plug. I was getting 11.2V (yep - need to take it for a driver today or charge it) with the boot open, and 0.01V with the boot closed (that's within the tolerance of the meter, so is probably 0).

    All my lights are LED... I used my DC Clamp meter to further test it, and it was drawing 80mA when on with the light reconnected, and 0mA when off with the hatch closed.

    I'm wondering how it detects if the boot hatch is open or closed. I can't see a switch anywhere. If it's mechanical, it may have water ingress, or there could be water ingress into the connections to the sensor.
     
    #3 The Professor, Apr 27, 2020
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  4. CooCooCaChoo

    CooCooCaChoo Active Member

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    Probably detects the hatch open/closed in the latch somewhere.
     
    #4 CooCooCaChoo, Apr 27, 2020
  5. kithmo

    kithmo Couch Potato

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    An old Austin Ambassador I used to have had a mercury switch for the hatch light.
     
    #5 kithmo, Apr 29, 2020
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  6. sam spade 2

    sam spade 2 Senior Member

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    Current draw is not measured in volts.
    It is not unusual for an electronic "switch" to show a small "off" voltage like that.
    It takes a very high impedance meter to even see it.

    While it will supply zero current, effectively, it might cause an LED to glow faintly.
     
    #6 sam spade 2, Apr 29, 2020
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