[TMVB]

Finally was able to pull off what I had been wanting to do all along - extend the factory head unit somewhere else in the car so that I can add an aftermarket head unit, and keep the factory connected to power the upper display. This way my backup camera, MPG screens and settings remain intact.

So many have said that this can't be done, I didn't want to risk damaging some of the cables so I buried it inside the dash underneath the climate controls. Not an ideal solution.

Thanks to @timeshifter who found an audio shop in California that had done this. A couple of phone calls and email exchanges and I learned everything they had done. Turns out this is a lot easier than people were thinking.

I made a tutorial video that should answer all questions and that's posted here:

Here's what the final product looks like with it mounted inside the trunk.

 

[TMVB]

This is what the factory video cable looks like. The one everyone was worried about cutting. It's just a simple, two connector, shielded cable. I used microphone cable to extend. Solder both connectors, and solder the shields together and it works great.

 

[TMVB]

Here's my connector graphic and the three cables that I made to extend the head unit. Again, full details are in the video.

 

[RobRac]

Great writeup and useful info. Not sure if you chose the best place for the factory radio but I will certainly follow your steps if I happen to buy a model without navi.

 

[TMVB]

Great writeup and useful info. Not sure if you chose the best place for the factory radio but I will certainly follow your steps if I happen to buy a model without navi.

Thanks. The car I was using as an example had it mounted in the center facing rearward. I didn't like that. Took away too much room.

Spent hours in the trunk trying different options. For such a small box there are surprisingly few options. But if you do it I will look forward to seeing what you chose.

 

[timeshifter]

Thanks so much for doing this and documenting it so well @TMVB !! I've had my Accord for 3.5 years and for the first time there is a solid, reasonable solution for adding an aftermarket head unit to my Accord. Well done.

 

[Lashlee]

Looks great! Thanks for posting it!

 

[fighter1313]

Terry, amazing work!:nerd Great presentation. I am considering to do the same and would highly recommend everybody to go this route. Metra is questionable even with all the firmware updates and who knows if the Axxess black box would last.
Appreciate you time and efforts very much.

 

[seldomseen]

Looks good! Should you take it a step further and install the head unit into a basic custom housing.

 

[TMVB]

Terry, amazing work!:nerd Great presentation. I am considering to do the same and would highly recommend everybody to go this route. Metra is questionable even with all the firmware updates and who knows if the Axxess black box would last.
Appreciate you time and efforts very much.

Thanks! Until someone comes up with a reliable and decent looking set of screens for the upper display, I think this is absolutely the way to go. iDataLink makes some really nice stuff and they've said they're working on an RR Maestro solution for our Accords. But nothing yet.

Looks good! Should you take it a step further and install the head unit into a basic custom housing.

Good suggestion. From here there are really two ways to go. Make a custom housing as you suggest. Or figure out how to extend the faceplate from the head unit box. Doing that would allow mounting just the faceplate inside the cabin where it's more accessible. I'm going to play around with the faceplate connector and see what's possible.

 

[fighter1313]

Do you think that harness of your design can be made by somebody as competent as you in numbers and sold at eBay or at craigslist? I am interested in buying one!

 

[TMVB]

Do you think that harness of your design can be made by somebody as competent as you in numbers and sold at eBay or at craigslist? I am interested in buying one!

No idea if this would be worthwhile for someone to take on. The market size would be pretty small I suspect. I mean how many Accord owners would want to do this? My guess is only a handful. Lots want to go aftermarket so if Metra can pull their heads out of their backside or if iDataLink ever solves it, there will a large market for adapter kits that keep the upper display but don't require you to keep the factory head unit connected. But for now not many would want to extend their factory head unit to the trunk.

I'm certainly not interested in making this for others. I did it for myself and am willing to accept my substandard soldering skills. And if anything goes wrong in the future, I only have myself to blame. I wouldn't want someone to buy this from me and have it go south and they end up feeling like they didn't get what they paid for.

One of the reasons I was so explicit in the video and went step by step on how to do this, was to give those that are interested the confidence to try it themselves. If you're still not there yet, take my video to your local audio shop and show them what you want. Maybe they would be willing to do it for you provided that you picked up the used head unit.

Edit: But if you decide to tackle this, PM me and I can answer any specific questions, provide my wiring schematic, and help if you get in a bind. One thing to keep in mind is that I already have another harness that connects my steering wheel control, Kenwood head unit, and the factory 24 pin harness. So if you were going to start from scratch, you would need to either build that harness first, or just build a single one that accomplishes both objectives (tie in aftermarket and SWC and extend cables to the trunk.) Again, PM me if you have questions.

 

[fighter1313]

You have answered my question and I am PMing you for a detailed info.
I personally like the OEM interface of the iMID and I do not like the Metra's one. With Metra's we will not be able to see full Settings or Diag screens and this is even on the condition if everything else will work without glitches.
For the beginning, I would like to have a list of materials (other than an aftermarket unit of choice itself) to complete this project from scratch and to place the OEM HU to the right upper space of the trunk as in your car. This so far is the best option, and you should deserve a praise from everyone on this forum for developing the algorithm of doing that.)
Thanks again

 

[TMVB]

If you're going to start from scratch, it will be slightly easier. Not much, but slightly. You won't have to buy as many Metra A harness connectors (70-1729 and 71-1729).

The hardest part will be sorting out how to connect the following:

A1 (Chassis Ground) to the Aftermarket HU, Factory HU and SWC.
A3 (12V Constant) to the Aftermarket HU, Factory HU and SWC.
A24 (Acc) to the Aftermarket HU, Factory HU and SWC.
A11 (SWC Ground) gets disconnected from Factory HU and joins Chassis Ground (A1).
A22 gets disconnect from the Factory HU and connects to SWC ONLY.
C9 gets disconnected from Factory HU and connects to SWC ONLY. This is the only factory wire that has to be cut. Unless you want to build a C Harness extension by harvesting the female C connector from the donor HU.

Oh and you should still connect the Aftermarket HU Illumination/Dimmer wire to the middle grey wire in the Climate Control harness.

If you use the attached wiring schematic, you can't go wrong.

As for a shopping list, here you go:

Cat 6 Cable. Get 2 of these. One for G and one for D.

Microphone cable. Get one of these for H harness.

Speed Wire. Get one of these for A harness.

Metra 70-1729 Female connector. Get 2 of these - one becomes a pin donor.

Metra 71-1729 Male connector. Get 1 of these.

1/2" self closing braid.

I didn't include solder, heat shrink, electrical tape and a couple other odds and ends.

Hope this helps.

 

[fighter1313]

Thank you! I have not seen this reply and kept firing PMs. It will help a lot.


More items for the list?

You did not mention in your shopping list a "donor HU" for harvesting male connectors. As a newbie, I do not see the whole picture yet...((( Do we need another OEM HU to harvest male connectors for A, D, G and C? Which type of cable should be used for a C-harness? Plus we need to by a SWC harness.
Head is already spinning! And this is just the beginning...

 

[ITR1102]

Do we also need another OEM HU to harvest male connectors for A, D, G and C? And a SWC harness of certain type?

I checked eBay this morning and none of the LKQ head units had the connectors/pigtails from the harness included.

I plan to check with a buddy at Honda this week to see if he can source the connectors, but I don't have high hopes. If anyone else knows how we can acquire the needed plugs, please let me know. Even if a bulk buy is required, depending on the unit price it still may be worth doing. I would like a completely plug and play solution without cutting any factory wires.


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[TMVB]

I checked eBay last week and found 5 within a couple of minutes.


EDIT>

Found this one: http://m.ebay.com/itm/2013-2014-201...3D100408%26rk%3D5%26rkt%3D25%26sd%3D222056106781&_trksid=p2056116.c100408.m2460

They're out there.

 

[ITR1102]

Obviously my search skills are lacking... thanks

I need to check the wire harness part numbers unless someone can say for sure the 2017 has the exact same connectors on it.


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[fighter1313]

As I understand it now, we have to add to the shopping list two items:
Used OEM HU with cut wires for harvesting male/female connectors
SWC kit
Am I missing something else for complete project parts list?

 

[TMVB]

As I understand it now, we have to add to the shopping list two items:
Used OEM HU with cut wires for harvesting male/female connectors
SWC kit
Am I missing something else for complete project parts list?

You need an aftermarket head unit, a dash kit, and an antenna adapter. The rest depends on your install. RCA cables to aftermarket amp? Speaker wire to new speakers? Power and ground cable kit? Speaker adapters?

The complete shopping list all depends on your install.