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Backup Camera Detection from Reverse Wire

Discussion in '2002 - 2005 Ford Thunderbird' started by bpfastball, Sep 7, 2017.

  1. I installed an Android head-end unit (link) to replace the factory 6 CD changer and everything is working great EXCEPT when I try to connect a backup camera (link). I connected the detection wire and video cable to the appropriate points in the head-end unit, but when I connect the other end to the reverse light wire there is some low residual power (2-3 volts as measured by a multimeter) in the circuit even when the car is not in reverse. It is enough power that the head-end unit triggers its "show the camera image" mode, but not enough power that it actually powers up the camera - so essentially the head unit is stuck showing a "no image available" message. When I actually do put the car in reverse, I get a full 12v of power in the circuit, the camera powers on and I see the image on the head unit just like I'm supposed to.

    The two things I can think of to try are: (1) insert a resistor in between the reverse light and the detection circuit to try to absorb the residual power (but not such a big resistor that it will absorb the power when the car is in reverse and the circuit is at full power) or (2) see if I can get a relay with the detection side high enough that it won't be tripped by the residual power (I don't even know if such a thing exists).

    Has anyone else encountered this problem? Any suggestions?
  2. What you are seeing is the "bulb burn out detection system" which sends the low voltage to almost all bulbs on the car. The solution to your problem is going to require that you ( or a friend who is an electrical engineer ) create a blocking circuit which might be as simple as a 3V Zener diode or if the camera will not run on 9 volts, might need both a zener and a transistor switch. The components will cost less than 3 bucks but it will require just a little engineering.

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