I’ve been putting off getting the hard wire cable for my GPS for a while. I have a Garmin StreetPilot 2650, which is the last GPS to have both voice navigation and an NMEA data interface. The former is a necessity when driving in unfamiliar places, the later lets me interface it with other equipment, like an APRS tracker. Newer units have one or the other, depending on whether they are marine or automotive units. The only way to get at the NMEA interface is with the hard wire cable, which has the added benefit of not taking up a cigarette lighter socket, and can be connected to a switched circuit so it turns on and off with the truck.
!http://www.mollyandrich.com/images/11.jpg (Garmin 2650 Cable)!
The reason I put it off for so long is the description on Garmin’s site (and all of the reseller web sites) didn’t say which wires were what, or even what wires were available, and the image on Garmin’s site (and all of the reseller web sites) only showed four wires in addition to the serial cable connector. The reason this concerned me is I was afraid that the four wires were power, ground, speedometer, and backup lights (for dead reckoning). This doesn’t leave any wires for a speaker, which is part of the original cigarette lighter cable. I didn’t really want to lose voice navigation capabilities to get NMEA capabilities.
I finally ordered it, and I was pleasantly surprised to discover six wires, not four, meaning all of the functions are available (though one of the colors was different from the label). I did a quick and dirty job of running it to use at Wildflower, and I still haven’t actually connected a speaker to get back voice navigation, and my APRS tracker still doesn’t work, but it’s progress.