Subwoofer screw up
 

Hello all this is my first post on here so bare with me... About a year ago I decided to take on the task of wiring my own subwoofer and amp I got off of marketplace. I foolishly did not do enough research and sped through the wiring without much regard for what I was actually doing. I ended up pretty much cutting the whole wiring harness for the factory amplifier behind the back seats that I thought only powered the door speakers. Now my dash speakers are no longer being amplified because I removed the factory amp. Does anyone know if there is anything I can do still or is it too late?

Thanks in advance
Info:
Car: 2013 mt premium BRZ
Sub: Alpine S-W S-Series Dual 4-Ohm
Amp: Boss R1100M

Here is a link explaining how the trunk amp is wired:

https://www.ft86club.com/forums/show...7&postcount=35

You are correct, the amp is only used for the door speakers, not the dash.

Something else is messed up other than the amp.

Subwoofer screw up
 

@ so what is causing my dash speakers to not be able to stay clear past half volume? Are they powered from the head unit? I’m terrible when it comes to wiring and I struggle to understand simple wiring diagrams as you linked...

The front speaker wiring coming out of the head unit - splits - and goes to the dash speakers as well as the amp in the trunk. If the wiring in the trunk is shorted or incorrectly connected to an aftermarket amp it may be affecting (even damaging) the output of the head unit and subsequently the dash speakers.

Subwoofer screw up
 

@ okay thanks for the help. I will probably just end up cutting all the current connections and go back and solder them up nicely now that I know how to see if there were any bad connections causing resistance (I think that makes sense? lol)

Edit: so your telling me the fact that the factory trunk amp is completely disconnected and removed from the vehicle isn’t causing the problem? Just trying to better understand I’m not savvy when it comes to wiring..

Below is a picture of the two connectors on the side of the factory amp in the trunk. These would need to be unplugged to remove the factory amp. If this was done and nothing more - just leave the connectors laying there - the front dash speakers would continue to function as usual and the door speakers would be dead. Now, if these connectors have been cut off the ends of the wires and the bare wires connected to something else (like an aftermarket amp) in a less-than-ideal-manner there *could* be problems with the dash speakers.

Something else I noticed: Did you run a new 12 volt power wire up to the battery (or elsewhere) for the Boss R1100M amp? The factory power wire for the trunk amp is only rated and fused to supply 15 amps at 12 volts. The specs for the Boss R1100M indicate that it requires a 30 amp circuit - twice what the factory circuit is rated for. This has nothing to do with the speaker issue but you may blow fuses or melt wiring depending upon how hard you drive the amplifier. Just sayin' . . .

@
Yes I did run a new power wire from the battery through the firewall to the back and it’s grounded on the strut bolt I believe.

:thumbsup:

@so I have a update, I went back today and cut all the connections and one by one soldered new connections between every wire. Unfortunately it did not fix the problem. The sounds doesn’t stay clear past half volume on Bluetooth and is the same amount of sound as using a usb but is able to go to 80% on usb for some reason.. I have attached photos of the wires that I have left untouched and also a photo of all the wires being spliced from the trunk amp harness. Please let me know if you or anyone else sees any red flags. Thanks in advance. https://uploads.tapatalk-cdn.com/202...880e35b3d2.jpg
https://uploads.tapatalk-cdn.com/202...fe8a50454c.jpg


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I guess I am confused as to why you physically cut at the connector, rather than just unplug and tap into the source wires. That is neither here nor there at this point, but it makes it nearly impossible to put it back to factory to diagnose problems. Since that's the first thing I would normally do, I guess we'll have to dive in the deep end right off the bat.

It is nearly impossible to see what wires go where in those photos. It looks like some are being used twice, others looping around to somewhere, and others probably connected independently but for some reason under 1 piece of heat shrink. So here's what would really help:

You've got 5 wires from the car, Y, SB, LG, DG, W.
Tell us where you've hooked each color up to. Each should only connect to one wire on your line converter.