Heh, I'm having the same issue and was about to make a post about it. I'm really scratching my head over it.

My car has been converted to a manual, so I don't have the shift lock issue. I do not have a driver rear turn, map lights, or dome lights.

Turn signal circuit gets 3v, whether I have the turn signal on or not. Front driver signal and passenger side signals are fine. It is most definitely not the bulb.
Same goes for the dome lights, it gets 3v. On or off. New bulbs, same problem.
Visors are removed, and both front and rear overhead lights are removed, to verify they aren't causing a short. If I jump 12v into either circuit, they work as intended.

Resistance between ground circuit on dome and ground is 0.1-0.2ohm. Resistance between power circuit on dome and BCM is 0.1-0.2ohm. Resistance between power circuit and ground is infinite.
Resistance between driver turn signal and BCM is 0.1-0.2ohm. Resistance between turn signal and ground is infinite.

This tells me there is no wiring issue on either circuit.

Following the flowchart in the repair manual, next step is to replace the BCM. But, I have a spare BCM (programmed) here and it behaves the exact same way. My fuse F30 isn't blown, but I haven't tried swapping it yet, doubt that would help.

Did you ever get this figured out @tomat0 ? Any others have any suggestions to try?

I'm going to look into the shift lock circuit, and see if that leads me anywhere, since I didn't realize but it appears to be tied into the same power feed from the BCM.

 

...
My car has been converted to a manual, so ...

Sorry, I can't be of any help with your current electrical issue, but I would love to hear more about your transmission conversion (as would a great number of others here, I'm sure). Any chance you could make another thread describing your build process? Please, please, please!!

 

@tomat0 thank you for posting this! I thought I had been chasing different issues but now since I know they are correlated, I checked the power wire coming into the BCM from F30. Sure enough, I was only seeing ~4ish volts incoming, so that explains why the outputs were only seeing ~3v. If I jump 12v into there, my dome lights and driver tail light work as intended.

So I either have some high resistance or a short on that wire, time to investigate that further. I have had the dash all apart, so either is possible. I recommend you check yours if you have not figured this out yet. F30 goes into the BCM on X5 pin 3. The brown connector, red wire with green stripe at the top by the release tab.

 

^^ That's awesome fuzzkill. Thank you so much!

 

What a fun read on the New Caprice forum. Thanks @fuzzkill . I may have skimmed over any discovery, but noted that your display had been "Holdenized" but you weren't sure of any additional menus or features. It was probably done by Chris White at White Auto and Media, ( member @GTPprix here) and probably has the performance menu as well.
Excellent write up, good work, cute kid.

Chevy SS Instrument Cluster Holden / HSV Conversion & Performance Menus 2014-2017

Doing a Holden or HSV Conversion to your Chevrolet SS? Then you need this! You're choice of themes to match your conversion and performance menus to boot!

www.whiteautoandmedia.com

 

What a fun read on the New Caprice forum. Thanks @fuzzkill . I may have skimmed over any discovery, but noted that your display had been "Holdenized" but you weren't sure of any additional menus or features. It was probably done by Chris White at White Auto and Media, ( member @GTPprix here) and probably has the performance menu as well.
Excellent write up, good work, cute kid.

Chevy SS Instrument Cluster Holden / HSV Conversion & Performance Menus 2014-2017

Doing a Holden or HSV Conversion to your Chevrolet SS? Then you need this! You're choice of themes to match your conversion and performance menus to boot!

www.whiteautoandmedia.com

Yeah I've used WAMS in the past on my other manual conversion for the BCM reflash. On this car they were too busy to help me, took almost a week to even get a response, and then another week to tell me they can't do it. It's unfortunate, but I understand custom work is probably not what is driving the sales. My radio was already programmed, so I had the cluster theme/performance menu done along with the BCM and some other modules.

Thanks for the kudos, I'll be posting about it more when it's done 🔥

I'm stoked that the lighting issue is fixed now, and hopefully this can help others if they have this issue. FSM flowchart didn't help on this one, and I had been messing with it for more than a day and about to give up on it before I posted here.

 

Hey man truly sorry about that. We are short staffed and completely swamped with normal off the shelf work to the point that at that time we literally could not take anymore custom work as that backlog for that was already 4-5 weeks and didnt want to get in any further than that; again my apologies