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Garmin GX3 install and purchases

I’m deciding on Avionics and install in my Supercub. Do I buy a whole wired kit including GX3 engine inputs,auto pilot 3 axis with external control GMC 507, ADSB in Out Transponder and GTR 200B external head radio. Is there special tooling needed. How hard is this to do yourself. What is the Garmin install manual like to follow for your own install. Does anyone have any ideas on this subject.
 
I'm not a fan of pre wired kits. They never fit anything exactly right. Fabricating the harness for YOUR installation is going to give you a higher quality installation that can be sized to accurately fit your aircraft.
As to doing it yourself, how much experience do you have with aircraft wiring? There will be some tooling required for terminating the wires to individual connectors. Do you have the tooling or have it available? Have you fabricated harnesses before? DO NOT use solder type connectors for these harnesses. As to the G3X manual, it is miserable. All the information you'll need is in there, but it is a very difficult layout to search through.
This is a very complex wire harness, both to fabricate and to install. I'd advise against doing this yourself unless you have quite a bit of experience to draw on. If you do decide to do it yourself, find an avionics tech to supervise the operation.

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Any system that includes auto pilot connections is complex in nature and requires extra care to insure correct and quality installation.

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None of it is hard work but it is unforgiving. Garmin uses specialized CAN Bus wire and all their install info is on line including interconnect drawings. At the avionics shop I work with it’s all done very carefully and the real skill comes in when troubleshooting. At best I would say you may be able to do the hardware install and have an avionics shop build the harness, if they will even do that. Probably won’t if you’re certified.
 
To Bearhawk builders point, the Harness gets built on the bench and then rung out to verify correct pins.
Then it gets installed in the aircraft and rung out again by someone other than the installer.
Then we do a power ring out in case all other checks failed so at minimum power and ground won’t be going to something that would get fried.
3 ring outs by at least two people, after being built on the bench by a guy that has been doing it for years.
It just takes time, patience, and verification.


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The first thing you need to do is decide what sub-components you’ll add to the system. Comm, txp, WAAS GPS, GDL, etc aren’t required items but you’ll probably use most or all of them. Then decide where these boxes will be mounted and keep in mind some of them will need future access. Once you make a map you can determine the length of each harness, and the relationship between components matters since you’ll need to pin connectors that go to each and wires will branch from one component to more than one other component. To terminate the wires you’ll pin connectors that Garmin provides. The only tools you’ll need are good strippers and a good pin squeezer. And a good magnifier to read the pin holes on the connectors! Watch some videos about terminating shields.

I had much of my wiring done by a local avionics shop. It was expensive and it left lots of work that had to be done in the hangar. Mike subsequently did the G3X install for the Airframes 4-place show Cub that never made it to OshKosh and if we were building another Cub I’d skip the avionics shop assistance, but Mike is very good at wiring computer stuff, and that’s exactly what the G3X is. For me it would be a very slow process and I don’t have the patience.

PS- Mine has remote comm, remote ES txp, GDL39R, WAAS GPS, EIS, 2-axis AP. Pretty much the full meal deal.I can’t think of any function I didn’t use. The AP attachment to the flight controls is another decision but the wiring part is very simple. Just more connectors.

Hint. Get a TCW battery backup and power the G3X through it. The G3X will reboot when you start the engine if the power supply isn’t buffered. It’s nice to be able to turn on the G3X ahead of the engine.
 

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Another decision will be how to manage power to all the components. I had a discussion with a Garmin engineer and took his advice to use individual breakers for each powered box. Some guys use Vertical Power and skip the breakers. Do some research and use the G3Xpert support if you need advice. They've been a very good resource and they're very responsive even on weekends. I'm a happy customer.
 

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It’s a 900+ page install manual you have to dig through. And some of the components aren’t even listed correctly in it. The first one you do will take allot of care and time. The crimper is $300+. You will probably wasn’t a microscope to. I’m on 3rd one now so it’s easier, and I have all my wire labels in a spreadsheet, & checklist.


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I built the panel and did the install and had Approachfaststack built my harness. It all worked perfectly. Tim at approach was amazing, he sent a worksheet for the harness everything worked as advertised!!!
 

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I figured somebody would start making pre-made harnesses. If I knew of such a service when I bought mine I probably would have bought it. Now that Mike's all practiced up it would be a different story but not everyone has a resource like Mike. If time is money I'd rather spend the money. It would represent a good value for most home builders.
 
I was considering building the harness myself but would have taken considerable amount of time and if anything was incorrect the thought of frying something (its all expensive) caused me to pause. The panel built would also be quite an undertaking and time consuming. I happy with my decisions and the harness could not look any more professional.
 
I figured somebody would start making pre-made harnesses. If I knew of such a service when I bought mine I probably would have bought it. Now that Mike's all practiced up it would be a different story but not everyone has a resource like Mike. If time is money I'd rather spend the money. It would represent a good value for most home builders.

I do this quite often. But there are limits to how much 'pre wire' you can do before the wires go into the aircraft. Some things are easy such as audio panels. I stub out the wires for the audio/mic/ptt for each item and install a connector. That way any radio added or removed simply needs to mate with the connector on the stub wire. The problem comes with the raw ends of the wires. Since no two aircraft are set up the same and no two installers route wires the same, the raw ends need to be fabricated long and cut to length once installed. The termination of these wires is up to the installer and out of my hands if I fabricated the harness. Single conductor wires are easy, just cut to length and crimp on a ring terminal. The biggest headaches are with shielded wires or any wires requiring a non typical connector. If you don't have the tooling or the experience, this is where the problems will be.

And remember that the 'time savers' like Vertical Power or FastStack units take up more room than traditional methods.
 
Not sure about price as it can vary and you can look around for deals from different suppliers.

As for function, both units are very similar with a display and add on units for expansion. If you're not sure which one will work for you, the best thing you can do is push the buttons on both. Buttonology is a very subjective thing. The controls on one unit may be perfect for one guy but never work for the next. Don't let anyone make up your mind for you.

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not sure if this will share correctly.... this is my spreadsheet of my wire lables for G3x....

edit... try this link instead first... https://docs.google.com/spreadsheet...JZ7iVRYj2oXbVQMWnhRKGGLmvaiw9YBXfNqoM/pubhtml


old link, not sure this one is useful for you...
https://docs.google.com/spreadsheets/d/1u1ao4pUVkAfvI6hu1gtR_bfcXDg_er70s3BtQO6VF8A/edit#gid=0

I use the "=CONCATENATE(A2:J2)" function to make each label (of appropriate) row?

what's connected on one end, what's on the other... print 2 dymo heat shrink tube labels and place at each end of wire.... so you can tell where it's going and what pins to connect it to...(the colon ":" separates the two wire ends... the "S" is concerning how to or not to terminate the shield at that end)

I copy and paste them from a PDF version of the spread sheet, to the label printer, so as to not have any new chance of making a new entry error...

probably not technically correct, as I chose to call white wires my grounds/lows... but so be it, that what I do... garmins drawings vary in what colors they choose also....

I have a couple different versions of this for specific fuselages(wire lengths)... 4 place 18.. or normal 18 cub...

this way I ONLY NEED to go through the install manual's 900 pages ONCE, and then I can verify I did it right after first install....

so far the magic smoke stayed in, and things seemed to work...

It also is a nice wire by wire checklist...
 
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