Update: I replaced the radio fuse with no noticeable change. But did notice that when I use the accessory mode, and even the run mode, without the engine running, everything works fine: radio, HVAC, blinker sounds. When I start the engine, the problems start: radio, HVAC, indicator lights going on an off, speakers crackling. I informed the dealership of my findings and am waiting for a response. (I didn’t OK the radio replacement yet.) Also waiting for a response from Chevrolet after again escalating. I tried to speak with the Chevrolet technical assistance center, but I can’t. They only communicate with the dealer.
I also experimented with removing the display fuse. Problems still existed, but you can’t control anything at the display: radio and HVAC, and no indicator lights illuminate.

 

Another dealer swapped out the radio with a used one at no charge. It didn’t solve the problem. He put the original back.

Pursuant to another owner’s request with the same problem, I reported the issue to the NHTSA and included my GM case number.
I have another dealer appointment next week where they again will work with GM’s TAC.

A record I’ve been keeping:

Problem: Radio goes on and off, speakers crackle, screen goes in and out, sometimes blank with light and sometimes goes black. HVAC indicator lights flashing, fan speed and blinker sound going on and off. Seems to take a few minutes before the problems start, longer when first starting vehicle.

Alternator disconnected (by dealer):

Problem went away. Working properly. New alternator didn’t solve problems.

Radio/HVAC control head replaced (by dealer):

Did not solve problems.

Fuse Tests:

Display fuse removed only (by customer):

Radio problem still encountered as reported initially, going in and out. No display and no control over anything: volume, channel selection, HVAC.

Radio fuse removed only (by customer):

Radio doesn’t work, no blinker sound, and no display, but HVAC works properly: no indicator lights flashing, working properly; no fan going in and out, working properly.

All fuses in, ignition on but engine not running (by customer):

Everything works without any problems. Display shows everything, no in and out of fan speed, indicator lights, and blinker sounds all good. Radio playing is consistent, no speaker crackling. All working normal.

Radio test (by different individual)
Plugged in used radio. HVAC indicator lights flashed so original reconnected.

Alternator test (by customer)

Battery voltage at 12.5.
When engine running, voltage starts around 14.8, rises to above 15; spiked to 15.15 and 15.20 at under hood connections.

Negative voltage drop at .01; .02 with accessories and lights on.

Chassis ground test at .02

Positive voltage drop: couldn’t complete because of limited access.

 

The dealer and TAC have determined it is the Body Control Module. There is much detail about the diagnostics performed, but the bottom line is it is the forth recommendation, and the first three were wrong. And they don’t guarantee that it will fix the problem. I’m waiting for GM to get back with me on this cost and no guarantee issue. So far GM has not been much help. Anyone with a Gen 5 LS Camaro with similar problems should file a report with the NHTSA.

 

The dealer replaced the BCM today. It did not resolve the problem. Now we have to wait for a response from GM.