I know there are multiple threads on help and suggestions dealing with this topic, but this is by far the easiest way on the 2012 Honda Civic Si Coupe! I finally figured out the easiest way to run the power wire, remote wire and amp boost wire. It took me a few hours to do, but it was well worth it and it saved me lots of money, which is always good!

Listed below you will find step-by-step directions...

1. Disconnect your negative battery terminal
2. Look to the right side of your engine bay. You will see a black trim piece that runs along the right side. In the back of it you will find a rubber flap. You will be running your wire here and down along the fender to a plug below the hood latch.
   • View attachment 4405 View attachment 4406 View attachment 4407
3. From the inside of your car, remove the plug behind the fusebox. It's below your hood latch wire. Run a 2+' piece of wire up through the hole and out to the engine bay at the rubber flap. Tape the wire and your power wire together. Pull the wire down through the hole. Drill a hole through the plug. Slide the plug onto the power wire, don't forget to do this before you run your wire back through your car.
   • View attachment 4408 View attachment 4409 View attachment 4410 View attachment 4411 View attachment 4414
4. Look to Part 2 of this continued Post

Detailed Power Wire Run on 2012 Si Coupe - Part 2

Hopefully this posts correctly!

1. Now you must remove your rear seat in order to partially disassemble your back quarter panel. This will allow clearance for the wire to be run and also allow you to run the wire up under the seat to your trunk. Lift your seat up slightly, there is two spring-loaded clips that need to be disengaged in order to remove the seat, but you are not done yet. Between the middle passenger and left passenger there is a bolt that needs to be removed. After that, the seat comes out very easily. Don't forget to slide out the seat belt buckle clips from the seat.
2. Next you need to remove the first two trim panels and only the third one partially. But before you do that pop off the bolt cover at the drivers side seat belt attachment point. Unbolt the seat belt, place it in the back cup holder. Move to the front trim piece and slowly pop off and away from the car. Be very careful at all trim joints as they clip together with each other. The second trim piece (the long one) is removed by green pop clips too. Again, be very careful at the end of it where it clips into the third trim panel piece. Here they are held together too. The longer piece need to be pulled up and away. Be real careful as to not break it. The third panel as you move back the vehicle only needs to be partially popped away. You will know when to stop as you will be able to see this.
3. Now continue to run your power wire and remote wire (& your amp boost wire if you have one) along the outside edge underneath the weatherstripping. Its fits here perfectly. I zip tied my wires together at various points. Continue to run the wires back the 3rd trim panel piece to the side of the seat area and under the fold-down seat area by the bolt in which you will be terminating your ground wire too.
4. From the trunk, pull your wire through, connect to your amp. Terminate your ground wire on the bolt found underneath the carpeting that covers a plate and two bolts. This plate and bolts are found in the middle, at the bottom of the fold down seat area. Try and keep your ground wire under 18". My ground wire location tested out good as I checked it with a volt meter.
5. Reassemble your car in reverse order. Be sure all pop clips are accounted for and are not broken. They cost $2 a piece at the dealer!
6. Tap your remote wire to a fuse located underneath the dash. Pull the fuse using the fuse puller found on the bottom side of the fuse box cover found in your engine bay. Trim enough insulation off the wire to allow you to join the fuse and the wire together back into the fuse plug. On eBay you can find "low profile mini fuse taps." I may buy one. I chose to tap into the "Power Windows" 7.5amp fuse as I thought this was one of the least to be worried about if something went wrong.
7. Lift up the positive terminal cover and connect your power wire over the vertical post using a washer and a nut. I ran my power wire along the side and around the backside of the battery so it was not obvious. Give yourself a little extra wire in the fender and under seat so if you need it in the future, you have it. Be sure to have the appropriate fuse within 6" of the positive terminal post on your power wire.
8. Reconnect your negative battery terminal.
9. Hook up your LOC to your RCA's, connect the sub to the amp, Check your connections. (I kept my factory head unit and tapped into the rear subwoofer line to hook up my aftermarket 8" JL Audio subwoofer. Check out my other post for this mod.
10. Start your car (DO NOT run your stereo without the car on as the battery will die within 5 to 10 minutes!). Make your adjustments to the LOC, amp, and head unit and enjoy!

GOOD LUCK... I hope this helps!

 

Detailed Power Wire Run on 2012 Si Coupe - Part 2

1. Now continue to run your power wire and remote wire (& your amp boost wire if you have one) along the outside edge underneath the weatherstripping. Its fits here perfectly. I zip tied my wires together at various points. Continue to run the wires back the 3rd trim panel piece to the side of the seat area and under the fold-down seat area by the bolt in which you will be terminating your ground wire too.
   • View attachment 4421 View attachment 4423
2. From the trunk, pull your wire through, connect to your amp. Terminate your ground wire on the bolt found underneath the carpeting that covers a plate and two bolts. This plate and bolts are found in the middle, at the bottom of the fold down seat area. Try and keep your ground wire under 18". My ground wire location tested out good as I checked it with a volt meter.
   • View attachment 4424
3. Reassemble your car in reverse order. Be sure all pop clips are accounted for and are not broken. They cost $2 a piece at the dealer!
4. Tap your remote wire to a fuse located underneath the dash. Pull the fuse using the fuse puller found on the bottom side of the fuse box cover found in your engine bay. Trim enough insulation off the wire to allow you to join the fuse and the wire together back into the fuse plug. On eBay you can find "low profile mini fuse taps." I may buy one. I chose to tap into the "Power Windows" 7.5amp fuse as I thought this was one of the least to be worried about if something went wrong.

GOOD LUCK... I hope this helps!

The bolts to use for grounding...do you know what size it is? I think the ring terminals I have are too small to fit there and I might have to look for bigger ones on EBay...

Thanks....

 

Good walk through. I installed my subs today and took roughly the same route except I went through the grommet and not the fender.

 

I went through the grommet / plug and it led up to the fender on the inside of the engine bay. Where did yours lead? Did we both feed through the same place inside the car?

 

OMG thank you, installing my amp on thursday and this will help FOR SURE!!
but i have a Sedan, so getting it to the back may be a bit different but i'll figure it out
Thanks a bunch though!

 

Yeah I went through the grommet toward the middle of the firewall.

Sent from my Desire HD

 

thanks man, this was super easy going through that hole in the fender.

 

Hey your welcome! I couldn't find any detailed info on it and I didn't want to pay someone else. So I looked and looked and bingo there it was. Piece of cake!

 

I know there are multiple threads on help and suggestions dealing with this topic, but this is by far the easiest way on the 2012 Honda Civic Si Coupe! I finally figured out the easiest way to run the power wire, remote wire and amp boost wire. It took me a few hours to do, but it was well worth it and it saved me lots of money, which is always good!

Listed below you will find step-by-step directions...

1. Disconnect your negative battery terminal
2. Look to the right side of your engine bay. You will see a black trim piece that runs along the right side. In the back of it you will find a rubber flap. You will be running your wire here and down along the fender to a plug below the hood latch.
   • View attachment 4405 View attachment 4406 View attachment 4407
3. From the inside of your car, remove the plug behind the fusebox. It's below your hood latch wire. Run a 2+' piece of wire up through the hole and out to the engine bay at the rubber flap. Tape the wire and your power wire together. Pull the wire down through the hole. Drill a hole through the plug. Slide the plug onto the power wire, don't forget to do this before you run your wire back through your car.
   • View attachment 4408 View attachment 4409 View attachment 4410 View attachment 4411 View attachment 4414
4. Look to Part 2 of this continued Post

thank u for pics and info!!

 

Great process, I was going to use the big wire boot or make a new hole, but this process was easy and quick. Took less than 20 minutes.
Thanks for posting your idea.

Mr Roboto

 

No problem.

Are going to be putting a sub in the trunk or did you figure out if another aftermarket sub can fit in the rear deck besides the JL Audio CR800?

 

thank you for such a detailed thread!

 

No problem

 

Any chance this would work the same on a sedan? I swear I couldn't find that "plug location."

 

I was wondering the same thing. I'm installing mine on Monday and looking for the easiest route on my sedan. I'm not willing to go out the door to the fender. Ill drill a hole if I have too.


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it's should be the same between the 2 and 4 door, that's not a spot that would normally be designed different between the two cars...I wouldn't think

 

I wouldn't think it would be different either. I'll give it another look today, right now I'm going behind the weather stripping close to the door joint and into the fender, it doesn't look pro enough for me to leave it like that long term.

 

It's the same Batman. I did it today. Very easy process. Thanks for the DIY


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No problem guys

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Thank you so much, have an Si sedan and followed your diy to a tee for a sub install in the trunk. Thank you, thank you, thank you the pics made a roadmap that was easy to follow. Main diff on the sedan is that you do not have to remove the rear seat. Keep the detailed diy's coming.

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Thank you for this. I have a 2012 Civic EX and this worked perfect.

Thank you, again, for your time and effort.

Cheers,

Anthony

 

Thanks for the DIY. I used this yesterday on my new Si sedan. It worked great. Only problem was I pushed the plug in and it fell into the wheel well. I had to remove the liner in the wheel well to retrieve it. Thanks again!


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Thanks for the DIY. I used this yesterday on my new Si sedan. It worked great. Only problem was I pushed the plug in and it fell into the wheel well. I had to remove the liner in the wheel well to retrieve it. Thanks again!


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No problem.
Bummer! At least you were able to get it out!
Happy modding!

 

how do you get the kick panel off to even get to the plug?

 

Ohh boy, I don't quite remember... Very carefully. I think it slides out? Pm me if I forget to look.

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It's ok I ended up going through a grommet above the gas pedal but thanks anyway.


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Bummer. From the side its easier and there is no chance that your foot and power wire could meet, but I haven't tried your way and that might be just as good? That stupid kick panel shouldn't have been that hard to remove? Sorry I just can't remember off the top of my head.

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I'm about to use this and Batman900's DYI to install a single 12" sub with slot port box run by a 400 RMS amp. My amp has Speaker Level (High Level) Inputs so i'll be running the wires to the amp directly from the factory 8" sub. I have an LOC but from what i've read everywhere, it's better to use the level inputs if your amp has that option. I'll post an update once the install is complete in about a week. The pics are extremely helpful. Thanks for the guidance!

 

HLI would be better. Wish I could find mine for my amp. Good luck and you are welcome.

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Sub and Amp install complete! The guide here worked flawlessly and it looks like a professional install. The hardest and time consuming part, surprisingly, was prepping the sub, amp and all the wires. Running the wires from the battery to the back and hooking up the amp was easy and took only about 45 minutes total. All I have left is to clean up and hide the wires.


Thanks again for the guidance!!!

 

Sub and Amp install complete! The guide here worked flawlessly and it looks like a professional install. The hardest and time consuming part, surprisingly, was prepping the sub, amp and all the wires. Running the wires from the battery to the back and hooking up the amp was easy and took only about 45 minutes total. All I have left is to clean up and hide the wires.

did you interior lights dim?

 

Great post! Tomorrow I will be putting it to use. Does anyone know of a thread of this quality that demonstrates how to wire aftermarket amp from the stock sub? RCA converter


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How did it go?


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Excellent! Glad to hear that.

Other question - don't know. Good question. From what I have read you can't fit an aftermarket amp in the oem spot. Its too small.

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^
No.