DJ wrote:
Tyring to avoid the cost of buying a ready made cord. Any ideas out
there as to the various ways to construct a cable to download from
the computer to the GPS. Understand you need a serial DB9 female
plug, a 12 volt power source (I don't know amperage ) and of course
the loose wires from the GPS . I have a Garmin 178C and I do know
which color wire go where....what I need is some creativity or
hardware ideas as to how to get them all together and then still be
able to take my GPS and its cable and put itr back on the
boat,,,Anybody ever done anything like this before??????or am I being
penny wise and pound foolish for even trying?

The color codes for the various Garmin plugs are available from the Garmin
website. Invariably the blue lead from your multi-point plug on the 178C is
data out, and connects to pin 2 on the DB-9 plug. The brown lead is data-in,
and connects to Pin 3 on the DB-9, and the black lead is ground, and
connects to pin 5 on the DB-9. If you look at the DB-9 thru a magnifying
glass you will be able to see the pin numbers on the plastic moulding. You
only use the top row (5 pins)

You pick up the wires from the cable supplied with your 178C, which will
also have power leads. At the opposite end to the actual plug, the wires
terminate in a bundle of loose leads, some of which will be tied back if the
unit is already installed. If the unit is not yet installed, you will need
to pick up the positive supply with the red lead, and the negative with the
black lead. The DB-9 plug does not supply power to the unit, so all you need
connected to this plug are the blue, brown and black leads, the latter being
also connected to battery negative.

The 178C may well have other colored leads dependant on whther there are
alarms etc. set up. these can be ascertained from the website wiring
diagrams.

If you have lost the cable/plug to the Garmin, forget it, and buy a new
cable.

DB-9 self assembly plugs are available from most radio/computer shops. You
need to be reasonably competent with a soldering iron.

To take the GPS home, disconnect the plug at the back and leave the cable on
the boat!

Dennis.