Truck is limp after installing subs

[rkolman5]

This is my first post so I'm not sure the correct way to do this. I have a 2018 Silverado LT, my buddy and I installed subs in both of our trucks (his a 2019 Custom, wound up fine). We did everything as normal, disconnected the battery, ran the remote access fuse (#2), tapped into the driver B pillar speaker wires, grounded under the back seat behind the seat bracket, and plugged it all in. Subs worked just fine, but when we were messing with the sound system we noticed my cluster throw a million things. My truck now has no power steering (not even 2 of us can turn the wheel), abs light on, traction control light on, seatbelt light on, abs light on, everytime I turn the truck on my wipers turn on (even when off on the stalk) for about 5 seconds and just pause. I am completely lost and have no clue what is happening. We checked every single fuse in the cab and engine bay, tried disconnecting everything back to as close to stock as possible, factory grounds are fine that we could've come in contact with. Help pls I beg of thee.

 

EDIT: I forgot to mention, when the truck is running, the RPMs will drop to 0 every 1-5 seconds, but the engine doesnt actually drop RPMs or try to stall itself out. Looked over all wiring, took both battery cables off for an hour, held together for about 2 minutes, and started the truck, same issue.

 

Codes: U0121-00, U0073-00, B0087-05

Edited April 11, 2025 by rkolman5

[Snowcamo]

Check your wiring again.  You've got wires crossed or a dead battery.  My first two thoughts 

Silverado wiring .pdf

[rkolman5]

18 hours ago, Snowcamo said:

Check your wiring again.  You've got wires crossed or a dead battery.  My first two thoughts 

Silverado wiring .pdf 3.59 MB · 5 downloads

I'm not the most intelligent when it comes to wiring, most of my experience is from stereos and sound systems. I can say the battery is fine, fuses are fine, and I checked over my wiring, no crossed wires, positive to positive, negative to negative everywhere. Any other ideas?

 

[silveradosid]

the B0087 code is for the left rear impact sensor, check the wiring going to and in the left rear door. if wires are shorted it brings down the can network which probably why you have the other communication codes

[Snowcamo]

I suggest putting the wiring back to stock and see if things change. They should, they did for me. That's how I end up posting that wiring schematic every chance I get. Been there. It should go back to normal when you return the truck to stock.