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Schematic (or pinout) for the TA-20

Does anyone have a schematic or know the Pin-out that Garmin uses on the TA-20?
I have a nuvi 2597.

Pin 4 on the USB Mini connector is not normally used, and I am assuming that Garmin uses the wire on pin 4 as the Traffic receiving antenna, along with maybe a “Pull Up” connection inside the 12 volt plug to allow the device to 'sense' that a TA-20 is being used.
My situation is that I have a flat USB cable currently in my vehicle that is power on/off keyed with my ignition. This is currently feeding an older Garmin without traffic capability. I would like to modify this wiring so that the nuvi recognizes the antenna.

(and yes, in the “About” section, the display indicates that MY 2597 IS equipped with the traffic receiver.)

(and yes, I understand that the TA-20 contains a 12vdc to 5vdc 'converter' to feed 5 Vdc to pin 1, with pin 5 being GND.)

Thanks for any help.


  • I don't have a schematic for the TA-20 but I can tell you what I see on the pins of mine. You're pretty close.

    Pin 1 +5V DC
    Pin 2 shorted to Pin 3
    Pin 3 shorted to Pin 2
    Pin 4 connected to Pin 5 via 17k4 ohms
    Pin 5 Ground

    Oddly, Pin 5 isn't connected to the shell. I thought it might have been. Hope this helps.
  • It does, thank you very much. 2 & 3 are shorted together so that the Garmin does NOT think it is connected to a USB (host - such as a computer). If Pin 4 is internally (in the Garmin) pulled up to +5 via a high value resistor (Say 1 Meg-Ohm or so) then the voltage divider can be sensed (inside the Garmin) and the wire in pin 4 capacitively coupled to the RF input of the traffic Receiver.
  • mike41 38 Points
    Any idea when the new Drivesmart 65 will be released for delivery.
  • Boyd 2010 Points
    Please start another thread if you would like to discuss the DriveSmart 65, that really has nothing to do with this discussion. FWIW, I see that the DriveSmart 65 is in stock at GPSCity, so it is probably available elsewhere too.
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