Footwell lights 2022 refresh Silverado

[RedLT]

So there's plenty of posts for footwell lights for 19-21 models using the BCM X1 pin 23 wire as a trigger  source to activate the dome lights when opening any door. Helping a buddy with his 2022 refreshed RST and discovered the BCM has completely changed from previous models, there's 2 rows of plugs now. Have looked at the gmupfitter manual but not getting very far, have unplugged each plug on the BCM one at a time but the dome lights never went off. Also tried the overhead console the gray plug pin 13 which seems to provide signal to the overhead LED but it only reads about 7.5 volts which didn't provide enough voltage to tap into for the trigger source. Has anyone attempted this mod on the refreshed model? Could sure use some help!

Edited August 11, 2022 by RedLT

[2020RSTBorla]

8 hours ago, RedLT said:

So there's plenty of posts for footwell lights for 19-21 models using the BCM X1 pin 23 wire as a trigger  source to activate the dome lights when opening any door. Helping a buddy with his 2022 refreshed RST and discovered the BCM has completely changed from previous models, there's 2 rows of plugs now. Have looked at the gmupfitter manual but not getting very far, have unplugged each plug on the BCM one at a time but the dome lights never went off. Also tried the overhead console the gray plug pin 13 which seems to provide signal to the overhead LED but it only reads about 7.5 volts which didn't provide enough voltage to tap into for the trigger source. Has anyone attempted this mod on the refreshed model? Could sure use some help!

Is 7.5v enough to trigger a 12v relay coil?  Does anyone know what the X1 pin 23 is putting out for voltage?  

Edited August 11, 2022 by 2020RSTBorla

[RedLT]

 

Not enough to run the relay. Previous models X1 pin 23 outputs 12 volts.

 

 

[2020RSTBorla]

On 8/12/2022 at 10:40 PM, RedLT said:

 

Not enough to run the relay. Previous models X1 pin 23 outputs 12 volts.

 

 

What about this?  https://www.amazon.com/TWTADE-Electromagnetic-Indicator-Socket-YJ2N-LY/dp/B098DTXQSH/ref=sr_1_9?keywords=6+volt+relay&qid=1660569750&sr=8-9

 

If you are worried about the extra 1.5v on the coil you could use a step down like this:  https://www.amazon.com/DZS-Elec-Adjustable-Electronic-Stabilizer/dp/B06XRN7NFQ/ref=sr_1_6?crid=10EDGCIRFUYNZ&keywords=dc+step+down+buck+converter&qid=1660569931&sprefix=dc+step+down%2Caps%2C75&sr=8-6

 

The coil side is low amp draw (150-200mah I believe) so you shouldn't have any heat issues with the step down dropping it 1.5v (7.5v to 6v).  The step down can handle up to 2A stock and 3A w/heatsink.  You can get some clear heat shrink and heat shrink the step down.

 

You can test it on the bench.  Just hook the coil side up with step down and power it with 5 batteries (5x1.5v=7.5v) and test to make sure the coil engages and also check the heat of the step down after a few minutes.

 

You would adjust the step down by hooking it up to your pin 13 and using a multimeter on the output to read the voltage as you turn the adjustment screw.  You could also adjust the voltage on the bench, but I would double check it when installed in your truck

 

This is where I would start if I was doing this project.

Edited August 15, 2022 by 2020RSTBorla

[RedLT]

On 8/15/2022 at 8:33 AM, 2020RSTBorla said:

What about this?  https://www.amazon.com/TWTADE-Electromagnetic-Indicator-Socket-YJ2N-LY/dp/B098DTXQSH/ref=sr_1_9?keywords=6+volt+relay&qid=1660569750&sr=8-9

 

If you are worried about the extra 1.5v on the coil you could use a step down like this:  https://www.amazon.com/DZS-Elec-Adjustable-Electronic-Stabilizer/dp/B06XRN7NFQ/ref=sr_1_6?crid=10EDGCIRFUYNZ&keywords=dc+step+down+buck+converter&qid=1660569931&sprefix=dc+step+down%2Caps%2C75&sr=8-6

 

The coil side is low amp draw (150-200mah I believe) so you shouldn't have any heat issues with the step down dropping it 1.5v (7.5v to 6v).  The step down can handle up to 2A stock and 3A w/heatsink.  You can get some clear heat shrink and heat shrink the step down.

 

You can test it on the bench.  Just hook the coil side up with step down and power it with 5 batteries (5x1.5v=7.5v) and test to make sure the coil engages and also check the heat of the step down after a few minutes.

 

You would adjust the step down by hooking it up to your pin 13 and using a multimeter on the output to read the voltage as you turn the adjustment screw.  You could also adjust the voltage on the bench, but I would double check it when installed in your truck

 

This is where I would start if I was doing this project.

 

Thanks for your input, yes I have thought of a buck converter but think that would complicate the project and thoughts of heat issue would leave me restless. These new refresh models are so new I guess not too many folks have dive into these.  Hoping for a pro schematics person to chime in or may have to sideline this mod until someone can come up how or what triggers the door light.

[RedLT]

 

Conducted another test on pin 13, strangely when using a multimeter to test for voltage it reads about 7.5v but is drops to about 5.6 volts when I probe pin 13 with a circuit tester to verify it is hot and then retest with the multimeter. Tested multiple times and same result, once it reads 5.6v it stayed 5.6v constant. so we let the truck sit for about 15 minutes with door closed then retest with multimeter on pin 13 and held it there between 1 to 2 minutes and for whatever reason the voltage drops from 7.5v to 5.6v on it's own. So it's like the initial door opening triggers the 7.5v and as the door remain open it drops to 5.6v. Didn't see/notice the dome lights dimming.

[Minmax]

I too have been trying to chase down this issue on my 2 week old refreshed Sierra Elevation. I am thinking the easiest, most accessible place to do an input is in the rear seat map lights (it’s only 5 wires, ground, 2 PWM signal wires, and 2 12v wires). I tried patching in an LED strip to the 12 volt signal path, but it is a monitored circuit, it DID light the LED strip (dimly) and then also dimmed down the rear map light (even after it was all unplugged, the map light signal path was remembered by the BCM, so even with nothing hooked up, the map light was still dim, had to do a battery reset to get it back to full brightness). I think the way to break out these signals is to make a break out box of sorts to the rear map light. I came into this truck while coming out of a 2017 Canyon that I up fit a Diode Dynamics solid white kit to, and it worked flawlessly. It came up and faded in with the domes I converted to LED’s, faded out with them, and when any door opened, it came on, and when commanded for domes through the switch they came on just the same as the overhead lights. This vehicle is completely different with everything being a pulse width modulated signal, so it’s much harder to “tap” into without screwing it up. I want this same setup in this truck and I would be done modifying for the foreseeable future. If the guts of a rear map light were remodeled in a way that it could monitor the PWM signal, to then ramp up/ramp down a 12 volt circuit, the same way the PWM signal ramps up and down, I could see this being the best way to make LED floor lights come to fruition, but there’s an awful lot of resistors, capacitors, diodes, and small chips in the map light that may be harder to extrapolate out into what I want it to do. I managed to put lighted vanity mirrors in and an auto dimming rear view mirror without much issue, but this modification has had me stumped a bit.

Edited August 31, 2022 by Minmax

[RedLT]

On 8/30/2022 at 10:52 PM, Minmax said:

I too have been trying to chase down this issue on my 2 week old refreshed Sierra Elevation. I am thinking the easiest, most accessible place to do an input is in the rear seat map lights (it’s only 5 wires, ground, 2 PWM signal wires, and 2 12v wires). I tried patching in an LED strip to the 12 volt signal path, but it is a monitored circuit, it DID light the LED strip (dimly) and then also dimmed down the rear map light (even after it was all unplugged, the map light signal path was remembered by the BCM, so even with nothing hooked up, the map light was still dim, had to do a battery reset to get it back to full brightness). I think the way to break out these signals is to make a break out box of sorts to the rear map light. I came into this truck while coming out of a 2017 Canyon that I up fit a Diode Dynamics solid white kit to, and it worked flawlessly. It came up and faded in with the domes I converted to LED’s, faded out with them, and when any door opened, it came on, and when commanded for domes through the switch they came on just the same as the overhead lights. This vehicle is completely different with everything being a pulse width modulated signal, so it’s much harder to “tap” into without screwing it up. I want this same setup in this truck and I would be done modifying for the foreseeable future. If the guts of a rear map light were remodeled in a way that it could monitor the PWM signal, to then ramp up/ramp down a 12 volt circuit, the same way the PWM signal ramps up and down, I could see this being the best way to make LED floor lights come to fruition, but there’s an awful lot of resistors, capacitors, diodes, and small chips in the map light that may be harder to extrapolate out into what I want it to do. I managed to put lighted vanity mirrors in and an auto dimming rear view mirror without much issue, but this modification has had me stumped a bit.

 

Glad to hear that someone on the forum is also actively working this mod on the new refresh. So far they are proving to be a headache to figure out. Be great to hear more feedback.

 

[RedLT]

Putting some more thoughts to this and thought of how Amp Research running boards connect to the OBD that activates the board when the door is opened. So, has anyone installed Amp Research running boards on the 2022 refresh models? Could possibly probe which pin that trigger the steps?

[newdude]

On 8/11/2022 at 7:34 AM, RedLT said:

So there's plenty of posts for footwell lights for 19-21 models using the BCM X1 pin 23 wire as a trigger  source to activate the dome lights when opening any door. Helping a buddy with his 2022 refreshed RST and discovered the BCM has completely changed from previous models, there's 2 rows of plugs now. Have looked at the gmupfitter manual but not getting very far, have unplugged each plug on the BCM one at a time but the dome lights never went off. Also tried the overhead console the gray plug pin 13 which seems to provide signal to the overhead LED but it only reads about 7.5 volts which didn't provide enough voltage to tap into for the trigger source. Has anyone attempted this mod on the refreshed model? Could sure use some help!

 

 

 

 

New trucks it gets interesting because they are now on GM VIP aka GM Global B electrical architecture.  More modules and data communications lines than before. 

 

I don't think I'd tie in at the BCM as its now a LIN BUS circuit aka a communications data line to the roof console logic.  Might upset the LIN BUS line/BCM.

 

Here is the interior roof lamps, and then take a look at circuit 2854 in both schematics.

 

 

Edited September 14, 2022 by newdude

[RedLT]

20 hours ago, newdude said:

 

 

 

 

New trucks it gets interesting because they are now on GM VIP aka GM Global B electrical architecture.  More modules and data communications lines than before. 

 

I don't think I'd tie in at the BCM as its now a LIN BUS circuit aka a communications data line to the roof console logic.  Might upset the LIN BUS line/BCM.

 

Here is the interior roof lamps, and then take a look at circuit 2854 in both schematics.

 

 

 

Thanks for the pointer, I've looked at that schematic up and down, it's just too cryptic to me to decipher where to go from there but I'll keep staring at it until a migraine sets in .

 

[newdude]

2 hours ago, RedLT said:

 

Thanks for the pointer, I've looked at that schematic up and down, it's just too cryptic to me to decipher where to go from there but I'll keep staring at it until a migraine sets in .

 

 

 

Here's the description and operation of the system:

 

Dome Lamps

 

The dome lamps are controlled by door ajar inputs to the K9 Body Control Module (BCM). When any door is opened, the door ajar switch contacts close and the BCM receives a door-open input. The BCM responds by sending a serial data message to the A103 Roof Console. The Roof Console responds by applying battery voltage to the dome lamps illuminating the dome lamps. The BCM will also send a serial data message to request the dome lamps on when a door lock/unlock request is activated with the key fob. After all doors have been closed, the dome lamp will remain illuminated approximately 3 seconds after the last door closes. In the event that the dome lamp were to remain illuminated for more than 10 minutes with the ignition switch in the OFF position, the BCM will deactivate the dome lamp control circuit to prevent total battery discharge. The dome lamps will turn OFF using the theater dimming feature when controlled by the BCM.

 

 

So you no longer have direct power from the fuse to each of the dome lamp "modules", it all feeds into the roof console and then the roof console feeds the 2nd row lamps.  

 

Using X1 pin 10 at the roof or in that second schematic X8 pin 18 at the BCM would be a no-go as it's just a command LIN BUS circuit so sends and receives commands telling the dome lights what to do. 

 

I think you'd have to tie into the output circuits of the roof console so in that first schematic, X1 pins 7 and 8 are the switches for the 2nd row, 13 and 14 are 12v output to the lights.  

[Minmax]

I think the best and possible only way to do a footwell lighting retrofit is to tie in to the LED outputs in the roof module and rear roof module… but they’re soldered in, so it won’t be easy or pretty. That at least gets you a signal, but it can’t power the footwell lights as it’s too large a load on the circuit. So I believe it has to receive these signals, turned over to a bridging module, that will then be powered by another circuit off of the fuse panel to actually power the footwell lights. As the signal fades out on the domes, it fades to the bridge modules, and in turn fades the footwell lamps. I was a BMW master tech for a decade, never thought I’d see the day when GM’s wiring was as big of a pain in the ass, but here we are.

[RedLT]

7 hours ago, newdude said:

 

 

Here's the description and operation of the system:

 

Dome Lamps

 

The dome lamps are controlled by door ajar inputs to the K9 Body Control Module (BCM). When any door is opened, the door ajar switch contacts close and the BCM receives a door-open input. The BCM responds by sending a serial data message to the A103 Roof Console. The Roof Console responds by applying battery voltage to the dome lamps illuminating the dome lamps. The BCM will also send a serial data message to request the dome lamps on when a door lock/unlock request is activated with the key fob. After all doors have been closed, the dome lamp will remain illuminated approximately 3 seconds after the last door closes. In the event that the dome lamp were to remain illuminated for more than 10 minutes with the ignition switch in the OFF position, the BCM will deactivate the dome lamp control circuit to prevent total battery discharge. The dome lamps will turn OFF using the theater dimming feature when controlled by the BCM.

 

 

So you no longer have direct power from the fuse to each of the dome lamp "modules", it all feeds into the roof console and then the roof console feeds the 2nd row lamps.  

 

Using X1 pin 10 at the roof or in that second schematic X8 pin 18 at the BCM would be a no-go as it's just a command LIN BUS circuit so sends and receives commands telling the dome lights what to do. 

 

I think you'd have to tie into the output circuits of the roof console so in that first schematic, X1 pins 7 and 8 are the switches for the 2nd row, 13 and 14 are 12v output to the lights.  

 

This much information I am aware of, thanks.  I have tested pin 13 but it does not output 12v, it reads about 7.5v and then drops to roughly 5.6v.  Once it drops to 5.6v, the circuit stays 5.6v for unknown set of time, the closest time I can tell is maybe an hour before it resets back to 7.5v.

 

[matt99199]

That 7.5V that you measured was probably a PWM signal from the BCM to the dome light directly. Would need an oscilloscope to confirm.

I'm trying to confirm for the refresh models now in my post here (for anyone interested):

I'll be able to figure it out soon as I have contacts inside GM and also at the dealership.