GPS - Cables, Power & PC Sync




Introduction: GPS - Cables, Power & PC Sync

About: So what ideas would you like to try?

uTX pfranc

Garmin GPS units have unique connectors and cables for power, data and multiple connections.

Instructed here are the unique cables and DIY connectors available to make you OWN cable or data interface.

Many connectors are available for a FREE pledge to pfranc's worldwide volunteers who locally ship and stock DIY cable pieces.


Step 1: Assembly

First feed the wires through the holes in the mid section then solder or crimp (or both) the pins to the wires. Then one at a time place each pin in the bottom to hold it and with your thumb nail holding it in the slot, bend it up 90 degrees (see photo below). Then use the safety pin idea for final assembly.

The "Safety Pin" idea:
I don't have assembly drawings yet but Mr. Naoya in Japan sent me a great idea that makes assembly much easier. I call it the "Safety Pin" idea because a fellow in Kansas borrowed a safety pin from his wife and told me it worked really great! Here is the drawing Mr. Naoya sent to me:

Thanks very much Mr. Naoya. A couple of professional cable manufactures told me this idea has made assembly much easier!

Step 2: ETrex

The pFranc-connector for eTrex comes as a do-it-yourself assembly kit.

In the kit you will find 3 plastic parts, one screw and a metal strip with pins on it.
Gently bend the individual pins so they break loose from the rectangle piece of metal, so you will end up with 4 of these:

After breaking the pins loose, we will need to bend them.
I used a flat screw driver for that purpose.

First lay the pin, with the bended part facing down, in the plastic piece with the four square holes (picture 1).
Next use a flat screwdriver to hold it in that position (picture 2) and gently use your nail to push it up as shown in the three images above (picture 3). Repeat this step for all four pins.

Now get your wires and connect (solder) them on the pins you just did bend. After doing so, gently push each pin, one at a time, through the plastic piece with the large rectangle opening as show in the image below.

Now we need to put the pins in the proper position in the plastic piece we just used for bending the pins.

To make things a bit easier on you, use a needle to hold the pins in place. The illustration below shows you how.

Do this for all four pins.

TIP: While you're at it, make a note which color cable you placed with what pin. If you're nor sure what the pin numbers are, then take a look at the image at the beginning of the page.

After completing this for all four pins, gently move the two pieces of plastic together until it becomes one.

Do not yet remove the needle! The needle is good for some stability while assembling the connector.

Now we need to place the "hood" over the connector. It's tha last piece of plastic which we gently put over the cable. Make sure that the cable do not make any kind of shortcut here!

After putting that together, gently rotate the connector and insert the screw in the hole (on the side where the pins stick out). Do not use excessive force when tightening the screw. After that you can remove the needle and your eTrex connector is finished.

Step 3: Mac Users

How to make a Macintosh/Garmin cable
(For new Macintosh computers a Bluetooth GPS is the best solution!)
Brought to you by Clover Technology AB in Sweden
With this cable you can connect a hand held Garmin GPS to the printer or modem port of your Macintosh. The same cable also works with the Newton PDA.

What you need:

1 Din-8 connector, male
1 PoP connector (find nearest dealer at

The kind of cable you choose is not critical. Solder the tricky part first (the DIN connector).
You only use pins 3, 4 and 5.

Now to the Garmin end. Identify the pins in you Garmin - pull out the rubber protection on your GPS and look at the connector. You have a plastic ridge at 11 o´clock, we use this as reference. Clock-wise from this you have Data-in (at 12 o´clock) - to pin 3 of the DIN-8, ground (at 3 o�´clock) - to pin 4 and Data-out (at 6 o�´clock) - to pin 5.

If you also want to connect power this is OK as long as you use the right voltage (some Garmins should never be connected to more than 8 Volts - read your manual). Connect a power (+) to the remaining pin and ground to the same ground as the data uses.

Apple Macintosh and Newton DIN-8 connector:Pin
RS-422 signal name


Handshake output DTR
Voltage from Mac

Handshake input CTS
Input to Mac

Transmit data -
Voltage from Mac
to Data-in on Garmin

Frame ground

to ground (-) on Garmin

Receive data -
Input to Mac
to Data-out on Garmin

Transmit data +
Voltage from Mac

Gen. Purpose Input or no connection
Input to Mac

Receive data +
Input to Mac
in rare cases this has to be connected to pin 4

Step 4: ETrax

Amazing DIY's !

for our cables see below...

Step 5: DIY Warnings!


You can burn up your GPS with the power cable you make with my Plug. Be extra careful if you have a low voltage model, the ones with 5 pin plugs. Pfranc connectors lets you connect to the 5 pin models. The 5 pin models want no more than 8 volts! The 4 pin models can take 32 volts and some even 40 volts. Figure out what your unit can handle before making a power cable. If you make a cable that can supply more than 8 volts (like a cigarette lighter) then make it into a 4 pin plug by inserting the little plug plug I provide with the kit. (Get it? A plug for a plug is a plug plug?)

Be responsible. Save a Garmin. It could be yours. (BTW, The Rx data line is OK with COM port voltages (+/-12V), no problem).

(BTBTW, as of 12/1/2001 (5 years and 175,000 plugs later) I have not received one report of anyone burning up a GPS. Good going guys!

You MUST put a fuse in if you make a power cable or you could easily set your car on fire! Cigarette lighter sockets provide enough power to light up a cigarette and the wire in your cable. Your Garmin doesn't need much power and it's nice to use small wire so just make sure the fuse is right for the wire. A 1/2 amp fuse should be good for 28 AWG wire and larger. If your wire is smaller than 28 AWG you'll want an even smaller fuse. The good news is, every cigarette lighter plug I've ever seen has a fuse built in already so all you have to do is make sure it's the right amperage rating.

Address RF. You can add a ferrite bead to reduce RF (Radio Frequency) interference. Adding a cable is like adding an antenna to your GPS, a broadcast antenna not a receiving one. It can broadcast the RF generated inside. The FCC Compliance Statement in your Garmin manual explains your responsibility.

Any other issues, please let me know. Us pfrancs never expected this to be so successful. We are sure to draw fire as we get larger so we want to be the best world citizens we can be and set an example for others. An example of how to be successful using the simple powerful tools of trust, honor, freedom, cool people, and the internet! We want to follow all the rules. We want to be responsible and do everything right, and we think you want us to too --> so help out.

Garmin is a good company, an amazing company of amazing people. We think that in a small way our Pfranc project here helped Garmin become the #1 GPS manufacture in the world (though they became "the-best" - all on their own:), and that's why I continue to buy GRMN stock. every time I can.

Step 6: Give a Pledge...get a Connector WORLDWIDE!

HEREpfranc cables


FREE connectors for a ...'pledge'...

What's a Pfranc'?
It is short for:
(P)OP (Franc)hisee.
It is pronounced "frank", as in "lets be frank".

But I use "Pfranc" in sentences the same way as I would "franchisee", "distributor", or "my friend". POP is an acronym for Purple Open Project. Purple is the name we use (since 1983) and "Open" is the cool new way of the internet.

There are 2 rules of Pfrancdom that guide Pfrancs: HERE

Websters defines Franchise as ...... go see for yourself here:
Our Pfrancs are ordinary people --- almost like "Frank" of Nortel. Nortel first introduced Frank in a TV ad October 2000. They wanted to tell everyone about Frank like e-business. Here is a photo of "Frank" from the ad: It's a great ad, you can go to: Nortel networks web page and see it on-line! I thought it was funny because we've been putting "a Pfranc face" on our web site since 1996! "e-business to be more - human", wow, that's it! That's what is about! People! Not computers. Wouldn't it be cool if our presents on the net influenced the idea for the Nortel ad? Nah. But who knows? It is getting to be a pretty small (and frank) world. How's that song go? "...come together, right now, over me". I transcribed all the words from the Nortel "Frank" TV ad here. Just for pFun.
Early 1996 I needed a word and didn't like "Distributor", so I considered Team, Confederate, Guild, almost went with League, but then ran into Franchise. At first I hated it because I thought it meant owning a fast food restaurant. But I looked it up anyway and learned that I hated it for the wrong reason. Hmmm, this never happens with other things, does it? I discovered that "franchise" is related to words like "free" and "liberty", so wow, cool, this was meant to be, the direction, the direction I'm being driven in ... again. If the word fits use it, if it is too long, shorten it. New word for a new thing. Base of word is vast and interesting and .... means something. Look up "frank" too:

A Pfranc helps me acheive: "The Purpose". The purpose is simple and clear, however, working on it and acheiving it is not. The way to accomplish the purpose has evolved. The purpose of POP #1 is: To get Garmin connectors from my molding machine to anyone who needs one fast and easy. How we do that continues to evolve. If you have any ideas, let us have 'em!

All Pfrancs Have a Garmin GPS, wanted a DIY plug, are comfortable with E-mail, the internet, and English; they got 2 plugs from me, were so impressed with the idea of Pfrancdom they asked to become a Pfranc.

Pfrancs enjoy helping people, check their e-mail often, and will send two plugs for just a pledge to anyone who asks. Pfrancs know the language(s), culture, customs, and system in their country. They understand what Pfrancdom is about and are able to translate and represent the purpose and philosophy of Pfrancdom to people in their country. They are emissaries of Pfrancdom. Many Pfrancs are retired and enjoy Pfrancdom as a pastime that keeps them involved with other people who own a GPS. Others recognized Pfrancdom as an opportunity to grow a business - and several did!

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    Shadetree Engineer
    Shadetree Engineer

    2 years ago

    It would be nice to include Garmin's USB Mini-B, 5-pin connectors. I've been looking for any info on how Garmin uses this type of connector. Most people say that this port requires a serial to USB adapter. But, Garmin states that the port can be set to operate in a 'virtual serial port mode', I've seen one pinout that suggests the ID pin (pin-4) is tied to VCC (pin-1) and possibly this triggers an automatic changeover in some of Garmin's units. That could be wrong. The reason I am looking into this, is that I want to use a 3DR type radio modem to transmit DGPS corrections from my own base station, to a GPSMAP64. And to do so in a very compact & lightweight rig that can be carried out in the forest. So preferably only one single battery pack to run both the radio modem and the handheld GPS, with a serial datalink connecting the two. Base station is:

    with this antenna:

    Using a free data stream from a local CORS monitoring station, without the handheld, just for testing purposes - I am currently getting a GPS fix with an accuracy of about 3mm in all three axes. It would be nice to have the same location accuracy while bushwhacking property lines where line-of-sight is not possible