BCM wiring diagrams

kodiakdenali · October 4, 2020

Since the service manual for the T1 is not available anywhere yet (that I've found) does anyone happen to have access to the diagrams for the BCM wire harnesses? I'm looking to modify the behavior of a few lighting systems. There are some mods for sale out there so someone must have either figured it out or there must be information available somewhere. none of the mods do what I want however. for starters I'd like to turn the fog lights on automatically with the headlights.

aragrev7 · October 4, 2020

Interested as well.
What kits have you seen?

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kodiakdenali · October 4, 2020

4 minutes ago, aragrev7 said:

Interested as well.
What kits have you seen?

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Boost auto parts sells a couple of simple kits.

fog lights on with high beams, fog lights on with parking lights, task lights on with high beams.

Nothing against them at all, I'm glad that the aftermarket community is out there thinking things up and implementing them! but their kits are basically a diode and some wire taps, probably less than $1 in parts they sell for $20. Unfortunately they don't have a kit to turn the fog lights on with the headlights. The BCM's lights outputs are mostly relay control switched ground, the diode just makes it turn on two relays instead of one. pretty simple! I just don't know what wire to connect it to to get the result I'm after. I'm used to having the full service manuals for all of my cars.

aragrev7 · October 4, 2020

Interesting. I ask because I’ve always rewired my vehicles to have fogs on with parking when I can. Looks much better. I like the independent fog lights.
Also rewired my reverse lights to a switch to come on independent of gear - deal with tailgaters at night, and gave me access to rear view cam any time as well.

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EXSlider400 · October 4, 2020

https://www.gm-trucks.com/forums/topic/239277-all-lights-mod-with-selectable-fogs/

kodiakdenali · October 5, 2020

Thank you EXSlider400!

looks like a diode between pin 21 and pin 10 on the X5 connector would give me what I'm after. Exactly the information I was after. Do you by chance have the pinouts for the rest of the BCM connectors by any chance?

Edited October 5, 2020 by kodiakdenali

kodiakdenali · October 5, 2020

22 hours ago, aragrev7 said:

Interesting. I ask because I’ve always rewired my vehicles to have fogs on with parking when I can. Looks much better. I like the independent fog lights.
Also rewired my reverse lights to a switch to come on independent of gear - deal with tailgaters at night, and gave me access to rear view cam any time as well.

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I hear ya! On my last truck I had it all rigged up with a microcontroller operated lighting control box, designed and programmed it. I had it alter the behavior of all kinds of lighting systems on the truck. Lots of fun!

EXSlider400 · October 6, 2020

20 hours ago, kodiakdenali said:

Thank you EXSlider400!

looks like a diode between pin 21 and pin 10 on the X5 connector would give me what I'm after. Exactly the information I was after. Do you by chance have the pinouts for the rest of the BCM connectors by any chance?

https://www.gmupfitter.com/pdflists/view/45

kodiakdenali · October 6, 2020

13 hours ago, EXSlider400 said:

https://www.gmupfitter.com/pdflists/view/45

Awesome! thank you so much.

I kept thinking looking at all the features that trucks have to make them easy for customization for all manor of work duty...there must be information out there somehow on exactly how to use all of those features, where power is available etc. looks like this is exactly that kind of information. this is perfect!

kodiakdenali · October 6, 2020

hmm. I hope the information in those documents is accurate, I'm seeing some discrepancies or errors. Although it could also be my own lack of knowledge. In the Sierra 1500 electrical doc for example, Page 2-45 under high beam headlamps...did any 2020 sierra have bi-xenon lights or otherwise have solenoids with shutters? These descriptions also talk about the BCM providing b+ to various lighting systems which I thought were actually controlled by relays energized by the BCM (BCM provides ground), and not powered by the BCM directly. I guess if I decide to play with anything I will have to carefully verify the information and not just assume its all correct. I guess one should always do that though.

It can't be a document that's mislabeled from a previous year model because it also contains information on 2019+ exclusive features, like the multi-pro tailgate and some images clearly show the new body style.

Edited October 6, 2020 by kodiakdenali

Jason workman · December 22, 2021

I'm trying to put led accent lights in the foot wells of my truck. I saw a video on YouTube on how to do it. I tried to find the wiring diagram for the bcm for my year of truck, 2019 chevy silverado, but I can't find one anywhere. I want to tap into the wire for my dash light dimmer, so that way the lights will come on when I unlock the truck and when my dash lights come on. But im not sure which wire to tap into. Could someone please help me figure this out.

RedLT · January 1, 2022

On 12/21/2021 at 8:13 PM, Jason workman said:

I'm trying to put led accent lights in the foot wells of my truck. I saw a video on YouTube on how to do it. I tried to find the wiring diagram for the bcm for my year of truck, 2019 chevy silverado, but I can't find one anywhere. I want to tap into the wire for my dash light dimmer, so that way the lights will come on when I unlock the truck and when my dash lights come on. But im not sure which wire to tap into. Could someone please help me figure this out.

Most are tapping into the door light on the BCM, white connector X1 pin #23.

Danny Bosch · September 26, 2023

New mirrors with work , puddle and spot lights

Ivan Melendez · February 7

I have a 2022 Chevy Silverado 2500hd and I would like to add auxiliary lights to the rear bumper of my truck and have them connected to the cargo light switch with out them coming on all the time with the key fob. Is there anyway to do this? Or even better yet to connect the aux lights to the side mirror reverse lights?

Edited February 7 by Ivan Melendez

Bikerjon · February 8

4 hours ago, Ivan Melendez said:

I have a 2022 Chevy Silverado 2500hd and I would like to add auxiliary lights to the rear bumper of my truck and have them connected to the cargo light switch with out them coming on all the time with the key fob. Is there anyway to do this? Or even better yet to connect the aux lights to the side mirror reverse lights?

Wrong forum for your truck. This is for the 1500s. Pretty sure the wiring would be different on a HD. You should be able to find what you are looking for in the gmupfitter link above. Lookup the HD.