Stereo Mods - Adding an amp and harness

Knighti2 · May 14, 2021

Im looking to get the LLJ harness and asked them where to look for the vehicle connector they ask about (black/gray or aqua/tan). They said to look and I quote "they will be behind the glove box, above the rear seat".

For anyone that might know these connectors and location that statement confused me a bit. Is that both places, a mistype from them maybe, or the storage boxes in the rear seats above them?

kmoon81 · May 14, 2021

4 hours ago, Knighti2 said:

Im looking to get the LLJ harness and asked them where to look for the vehicle connector they ask about (black/gray or aqua/tan). They said to look and I quote "they will be behind the glove box, above the rear seat".

For anyone that might know these connectors and location that statement confused me a bit. Is that both places, a mistype from them maybe, or the storage boxes in the rear seats above them?

Passenger side front, below the right side of the glove box. I just stuck my phone camera near the floor board and turned on the forward facing camera and snapped a bunch of pics under the glovebox. After zooming on one of the photos I was able to locate my aqua/tan connectors in the jumble of wires.

Edited May 14, 2021 by kmoon81

Knighti2 · May 14, 2021

Thanks kmoon81. Yeah got an email me back clarifying what he had meant to type was glove box above "kick panel" and he had typed rear seat.

So I did find them but appreciate your insight.

kmoon81 · May 17, 2021

Ordered the JJL harness (with NO UNIT option) over the weekend so we will see how it goes!

Knighti2 · May 18, 2021

I ordered the harness as well. I did order the Audio Control LC7i as well. Killing me having to wait again for few weeks to get this all wrapped up as the sound in my truck as stock is way disappointing.

ero2 · June 7, 2021

Hey all! Not to hijack the thread or anything, but...

I have an elevation with the 8in screen, but no Bose. The sound is pretty rough, even for audio books, lol. I'd like to leave the stock wiring alone (guess I'm getting old?), but am not confident that simply replacing the stock speakers will bring much better sound...I listen to punk, metal, rock, etc. so don't need boom, just better low and mid. Would just replacing the speakers with higher end ones help? It looks like crutch field recommends 6.5 or 6x3/4 in the front, and 6x9s in the rear?

Everyone here that went with no amp, just speakers, still happy with that decision? Thanks!

03 Cobra · June 12, 2021

Hey Guys I am not an audiophile by any stretch of the imagination, and this may or may not be a good deal and it may or may not be a good set up but I thought I'd point this out. The link below takes you to one with an amp. The one w/o the amp is much less $$. Buy it before 6/30 and you get 20% off.

https://accessories.gmc.com/product/electronics/200-watt-subwoofer-and-200-watt-amp-kit-by-kicker-associated-accessories-19417165?model=Sierra 3500 HD&modelId=6581&bodyId=22&body=Crew Cab Pickup&wheelId=349&wheel=Standard Box&trimId=556&trim=SLE&driveId=8&drive=4WD&engineId=17733&engine=6.6L V8 GAS&bodyNumDoors=5&year=2021&make=GMC&categoryId=12013

deoutdoors · June 23, 2021

If anyone is interested in purchasing the kicker 19417165

send me a pm. Just pulled it out of my 6 month old truck that I sold.

make me an offer

49Justin Hail · April 19, 2022

On 3/12/2020 at 8:10 PM, Reaper5699 said:

https://lljcustoms.com/

He makes a harness that plugs in....has several options for it. I was going to order one, but settled on replacing the front 4 speakers and adding an amp/mtx solobaric.

I made an account just to thank Reaper for a post from 2yrs ago. I've been on the hunt for this harness for weeks now. CF is more and out of stock, Metra doesn't make them still supposedly and I'm not paying that much for Gen5DIYs version. So thanks Man. Spreading the word of this post too since no one I've asked knew about this.

DScott3370 · November 6, 2022

I’m updating this old thread with my experiences from modifying the 2020 Silverado Trail Boss stereo system and now more recently my new HD Duramax stereo system. On the first truck I ordered a harness from LLJ customs. Took a month and it did not work correctly. I got no response from him. I found John from Audio Integrated Solutions (AIS) on this site. Sent the harness to him and he corrected everything. It worked perfectly and the turn around time was days. This latest truck I contacted John and he built me a harness in a matter of days as well. His work is flawless. His knowledge is vast, and he knows these GM wiring schematics inside out. Send him a picture of the RPC tag on the door, tell him what you are installing and he will get it to you. For 200 or less… in my case

[email protected] (Is his email)

Edited November 6, 2022 by DScott3370
Added email address

CT Chevy Connoisseur · December 5, 2022

On 11/6/2022 at 8:02 AM, DScott3370 said:

I’m updating this old thread with my experiences from modifying the 2020 Silverado Trail Boss stereo system and now more recently my new HD Duramax stereo system. On the first truck I ordered a harness from LLJ customs. Took a month and it did not work correctly. I got no response from him. I found John from Audio Integrated Solutions (AIS) on this site. Sent the harness to him and he corrected everything. It worked perfectly and the turn around time was days. This latest truck I contacted John and he built me a harness in a matter of days as well. His work is flawless. His knowledge is vast, and he knows these GM wiring schematics inside out. Send him a picture of the RPC tag on the door, tell him what you are installing and he will get it to you. For 200 or less… in my case

[email protected] (Is his email)

Interesting that you had such as issue with LLJ Customs, you are the first I've heard to have any issues with them. The process with them was flawless for me and they were very responsive to my questions.

That being said, having options is always good.

DScott3370 · December 17, 2022

Best I can tell is that he was overwhelmed in late 2019. There were a few discussions about LLJ back then on the half ton forum. I’m glad to hear he got it together. I still highly recommend AIS.

Mshawn · November 10, 2023

On 3/11/2020 at 11:51 PM, MesaRat said:

Does anyone know if there are aftermarket general harnesses or loop harnesses that plug between the back of the infotainment system and the body harness? I want to be able to take the audio signal from each of the speakers, send it to the rear of the truck into a DSP and amp, and then back to the body harness and into the speakers. I don't want to cut factory wiring. I've checked Crutchfield and a little bit online but i don't seem to see anything for 2020.

New to GM trucks and dealer is currently locating my truck for a dealer swap, and appreciate any help or input.

Thanks

MR

What harness did you use for this? I want to do the same-thing with the door speakers. I would like a little more power out of them. I’ve replaced all the door speakers and the dash speakers. Thanks in advance

305CHEVYBOYZ · February 19, 2025

I have a 2022 chevy silverado 1500

Installed a kicker amp but I get feedback back from the radio like something loose you hear feed from the speaker, weird thing is the amp turns on Without the remote blue wire like it's getting power from the speaker rca jacks ?

Epsilon Plus · February 22, 2025

Anyone do a single sub box like something on the passenger rear to middle areas that fits nice? Trying to preserve the driver side rear under seat as I carry a tool bag of emergency stuff there. The GM Kicker would work but I hesitate spending $700 bucks on something that barely knocks with 200w.

EDIT: Found a box that fits nice on driver side, guess I can move my stuff over

Edited February 22, 2025 by Epsilon Plus