Need advice on subwoofer install

Chris walker · July 29, 2020

I purchased the LLJ customs harness. Its great quality and I experienced good service...It took a couple of weeks to come in but well worth the wait.

In addition consider fiberglassing your own enclosure....I fiberglassed my own enclosure using the frame for the organization tray in the AT4. I have one 8 powered by 500 watts and its more than enough...

Edited July 29, 2020 by Chris walker

Jeff Cooley · July 29, 2020

I purchased the LLJ customs harness. Its great quality and I experienced good service...It took a couple of weeks to come in but well worth the wait.

In addition consider fiberglassing your own enclosure....I fiberglassed my own enclosure using the frame for the organization tray in the AT4. I have one 8 powered by 500 watts and its more than enough...

Thanks I may have to go that route unfortunately or just pay a shop to do it. Its not like other vehicles I've done. Frustrating as hell. I've got the amp signal but my LOC isn't doing anything for it. The signal goes in but nothing comes out. I'm thinking maybe it's not a sound signal wire. About to throw in the towel.

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Rook126 · July 29, 2020

Don’t give up yet.
Looking back on your previous post, this concerns me. “Both putting out approclx 6.1v”

Hoping you didn’t tap into the center console lighting wires or something else.
Were your sub wires green and black like in my images? They should be a little thicker than most other wires, like around 16 or 14 gauge.
Without the aftermarket amp, hook the wires directly to a speaker to see if the cone vibrates with music. Do this briefly at low volume since you are changing the overall impedance with a second speaker.

Let us know what you find.

Jeff Cooley · July 29, 2020

Don’t give up yet.
Looking back on your previous post, this concerns me. “Both putting out approclx 6.1v”
Hoping you didn’t tap into the center console lighting wires or something else.
Were your sub wires green and black like in my images? They should be a little thicker than most other wires, like around 16 or 14 gauge.
Without the aftermarket amp, hook the wires directly to a speaker to see if the cone vibrates with music. Do this briefly at low volume since you are changing the overall impedance with a second speaker.
Let us know what you find.

Yeah I tried booking it up to a speaker and no sound. Both wires looked exactly like the picture. Thicker than regular too. I took it right off the bottom just like in the pic. There was another set all tapee up hanging loose that wasn't secured to the floor so I didn't touch those. I'm thinking I'm just gonna get the LLC bypass harness and just plug and play it. Easier and less headache. I may look at the other wires under there tomorrow but it's 36C here and hot as hell.

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Jeff Cooley · July 29, 2020

Further to this. I will try the other wires tomorrow. LLC wants 50 USD for shipping which is crazy. I'll see what I can find tomorrow. I'll let you know how I make out. Learning lots about my truck though! Lol

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Paul 2020RST · July 29, 2020

19 hours ago, Rook126 said:

I have a 2020 w/ Bose and was able to locate and access the sub speaker wire beneath the center console without removing the console or any seats. I haven’t seen anyone post on this method yet so here it is.
Remove the plastic side panel from the center console on the passenger side. Think it was held on by several panel clips.
Slide the passenger seat all the way back to expose a carpet seam at the bottom of the console. Pull the carpet flap and peer under the console towards the rear of the vehicle with a flashlight. You should see a thin harness wrapped in black tape anchored to the floor with zip ties. There are only two wires in the tape.
You should be able to get a hand or panel tool in there to wiggle the anchors loose from a threaded stud or bolt.
There wasn’t much slack in the harness but try to pull as much out as you can. Carefully snip the black fabric tape exposing a green and a blue wire. I can’t remember which wire was positive or negative. You will probably have to research wiring diagrams or someone may recall.
I scored and slid the wire insulation to the side exposing the copper wire and then soldered speaker wire to it. Sealed it and taped it back up and put it all back together.
Ran the speaker wire under the passenger seat rails inside a seam in the carpet to the passenger door sill. Then ran it inside the factory wiring track along the passenger side under the door sills to the rear seat where my LOC is located.
This may be difficult to follow so here are a couple images. I hope this helps out the installers out there.

Thank you very much!

no issues with the crossover points of the Bose amp?

Rook126 · July 30, 2020

No issue with the Bose crossover point which is probably around 60-70. I am able to set a lower frequency on the aftermarket sub amp. Sound output is more than enough that my permanent bass setting on the radio is minus 7. This allows music to be played a little louder without clipping and distortion.

Chris walker · July 30, 2020

22 hours ago, Jeff Cooley said:

Thanks I may have to go that route unfortunately or just pay a shop to do it. Its not like other vehicles I've done. Frustrating as hell. I've got the amp signal but my LOC isn't doing anything for it. The signal goes in but nothing comes out. I'm thinking maybe it's not a sound signal wire. About to throw in the towel.

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I always get some level of feedback when doing line taps. The LLC adapter is 100% clean with a good ground. I was surprised with the quality of the LLC adapter. Its top notch and plug n play.....and Im not affiliated with them at all.

Jeff Cooley · September 12, 2020

So how do you get the Center console out. Do you have to remove the seats? I can't find any videos showing how to remove it. It's all for 2018 and prior. I finally received the adapter and I'm ready to do the install in the morning.

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Paul 2020RST · September 12, 2020

9 minutes ago, Jeff Cooley said:

So how do you get the Center console out. Do you have to remove the seats? I can't find any videos showing how to remove it. It's all for 2018 and prior. I finally received the adapter and I'm ready to do the install in the morning.

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The Bose amp is behind the back seat.

Jeff Cooley · September 12, 2020

For the 2020 GMC Sierra 3500hd?

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Paul 2020RST · September 12, 2020

1 minute ago, Jeff Cooley said:

For the 2020 GMC Sierra 3500hd?

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Not sure about the 3500. The 1500 has it behind the back seat.

Jeff Cooley · September 12, 2020

Not sure about the 3500. The 1500 has it behind the back seat.

Hopefully someone pipes up. It feels like the speaker is under the console and for some reason I thought the amp was there. The back seat would be much better

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BigBird · September 13, 2020

Not sure about the 3500, but the amp in my 1500 is behind the rear seat. I used a LOC from A.I.S.-Audio Integration Solutions and a sub thump box with integrated amp. install was simple and easy. Hardest part was taking the back seat out when it's 100 degrees outside.

Baby boy · April 17, 2025

Hey i have a 2019 Tahoe with a Bose system in it i would like to keep the factory radio and do a Gm bose full system integration harness kit so I would like to put a LC7i so I can do subwoofer and a 4 channel amplifier I seen a video were you made one can you please tell me how much it would cost me for one my name is Tony email is [email protected]