Subwoofer Install Guide FK7

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I've been wanting to install a subwoofer system in my 2018 Honda Civic EX-L Hatchback for the last 2 months now, but didn't have the time. Kept debating on whether or not to call a shop and pay a kidney for them to do it, but turns out today I had the time, and I had some stuff lying around from an old build, so I thought why not throw it into the Civic? While I've had experience doing this before, I was confused about things that I learned as I went, and I thought someone might be interested in a step-by-step tutorial.

Required Tools & Equipment: Subwoofer, box, amplifier, wiring kit (Power, ground, RCAs, remote wire, speaker wire, fuse), Line Output Converter, electrical tape, wire cutters/strippers, solder gun or quick splices, metal clothes hanger, some towels, panel poppers, screwdriver.

Step 1. Preliminary Work: Determine where you want to wire your LOC. I decided to do mine behind the radio for sake of ease, so I had to figure out how to pull the radio out, but you can run wires from the front (or rear doors, but I've heard that isn't recommended for best sound) to the hatch area and have your LOC by your amplifier. This video showed me exactly what I needed to do; I would highly recommend watching it to learn how to pull the radio out. Then, figure out which wires on radio harness and LOC connect to what. Did some looking on the forums and found a wiring diagram for my FK7. The wiring may be different between trim-level and model of Civic, so beware of that when doing your research. For those with an EX/EXL Civic, this is what I determined:

Left Speaker Front POSITIVE = light green. Left Speaker Front NEGATIVE = light blue.
Right Speaker Front POSITIVE = Grey. Right Speaker Front NEGATIVE = Purple.
Accessory 12v Power = Red. Ground = Black.

Again, will vary from trim and & model; please do your research before installation. With all the research done, I simply wrote out a little chart to indicate what went to what so I didn't have to think/stress about it during the installation:
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Step 2. Getting Going: Unplug your positive/negative terminal on battery and begin the installation. Follow the video to take your radio out, and wire your LOC into your radio harness. Once that's done, start running your RCAs and Remote Turn-on. I simply routed them through an opening behind the radio into the driver footwell. If you want, you can run them across the dash behind the glovebox, and have them come out in the passenger footwell. Make sure to adjust your LOC, and make sure your wiring is correct and secure, prior to putting the radio back in place.
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Step 3. Run Your Power. I suggest using the rubber grommet BEHIND the battery for your power wire run. Use a knife or something sharp to carefully poke a SMALL hole into the top part of that grommet. Repeat that process inside the car, in the driver's footwell. Will need to remove battery, and maybe insulation inside the car, to see both grommets. Once you have your holes established, grab your power wire, some tape, your metal clothes hanger, and I recommend some WD40 or something with lubrication. Tape your power wire to the straightened metal wire clothes hanger, spray a little WD40, and begin trying to fish it through the engine bay grommet. Take care as there are wires in there, but if done correctly you will have no issues. Fiddle with the metal wire for a bit until you can see it poking through the inside grommet, then carefully pull all but 6-8inches of power wire through. I simply left it in my footwell for the time being.

Step 4. Safety. I cannot stress this enough, PLEASE use a fuse with your subwoofer setup. It may take you a few extra minutes to do this task, but it is worth it. I simply taped/bolted my fuse holder down on top of the car's fuse box, but you do what is most convenient for you. From there, run 3-4 inches of power from the positive terminal into that fuse, then the rest of the wire tuck around the battery and heat shield and down behind the battery, into the car. Make sure everything is secure, out of the way of any mechanical/moving parts, and not touching any pipes.
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Step 5. Routing Wires. Now that you have power, RCA, and remote wire in your driver footwell, you can start popping panels inside the car and running them down the side. Pop the panel around the hood release, the trim between the seat and door, and the bottom part of the pillar panel. Run your power first, simply tucking it under the carpet and away from where one might rest their feet. Once you have the remaining power wire in the second-row seat, do the same thing for your RCAs and Remote wire, trying to put a few inches between the two. Some have said to run power and RCAs on the opposite side of the car from each other, but I've never experienced any real issues running them down the same side as long as they aren't bundled together. It is all about how much work you want to do, and your expertise. Once all 3 wires were in the rear, replace the front / pillar trim pieces and pop the trim pieces between the seat and door of the second row. This point proved to be a bit challenging, but I found it best to simply route the wires under the trim pieces leading to the seat, under the seat and up into the hatch area. May need a second set of hands to reach from the hatch into the crack behind the second-row seats, and pull the wires through. From there, simply tuck everything away and make sure nothing is visible. Once you have all wires in the hatch, replace all trim pieces.
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Step 6. Almost Showtime! At this point you have all but your ground run to the back of the car. A solid grounding spot would be where the spare tire retaining bolt is. I simply removed my spare tire (I've never had the need for a spare, hence why I remove mine. You do what you are comfortable with; find an adequate unpainted piece of chassis) and used another bolt to secure tightly in place. With all wires run, it is time to hook up your amplifier! This part should be what those of you who are DIYers like myself should already know, otherwise you really should take this project to an audio shop. With everything hooked up and your subwoofer in, it is time to reconnect the battery and test everything out!

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That is the end of this guide! I hope someone out there learns something from this. This was a great learning opportunity for me and while it took me upwards of 5 hours (with water breaks, lunch break, rests) to complete, the end result was so worth it for me. If anyone has questions on my setup, on how I did something, or anything in this nature please feel free to ask here!

 

typebeat.mp3

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This is awesome man, thanks for sharing the knowledge.

I have a Type R, but I'm assuming that most if not all of these instructions directly translate? Sorry, I'm a complete noob with this type of stuff.
 
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rwk226

rwk226

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This is awesome man, thanks for sharing the knowledge.

I have a Type R, but I'm assuming that most if not all of these instructions directly translate? Sorry, I'm a complete noob with this type of stuff.
Thank you!! And AFAIK the Type R should be like the Sport Touring model in terms of wiring. But with it being a 2021, I can't say for sure. My recommendation is to look up a 2021 Civic Type R or even Sport Touring wiring diagram. Aside from the wires being different colors potentially, the guide should still apply to you.
 

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What LOC did you use? are you still running the same setup? Thank you great tutorial.
 
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rwk226

rwk226

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What LOC did you use? are you still running the same setup? Thank you great tutorial.
I used a PAC SNI-15, but just about any LOC will work. Just beware that a lot of brands have cheap components and tend to distort easily. Check out this and this videos on LOCs and what's good and isn't. Anything from PAC, AudioControl are great.

 

 
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