[Mr.RHOSH]

Good day everyone. So, it has been hot where I live. I knew my battery was about ready to be replaced due to some non start issues over the winter. The battery is OEM from 2016. I started the car on the 4th of July. It is not a daily driver. My dash and entertainment screen were blank for about 10 seconds, then they both lit up with all warning lights illuminated on dash. I have no speedometer, fuel or temp, the car will not allow me to take it out of touring mode, no back up cam, no turn signal indicators (although the blinkers do work on the exterior). Luckily I use the torque pro app, so I am able to view all the information I need on my phone screen (live data from the ECU). It displays all my temps, tach, speedometer, fuel level, ethanol level, gear indicator, voltage, and boost.
I replaced the battery but the issue remains. While researching this issue, I have found that the rear bumper harness seems to be the culprit. My question to the forum is : Other than replacing that harness, is there any way to verify that it is indeed the problem?
I have ordered the harness and of course, the delivery is one day before a track event I am registered for. Other than the fact I cant put the car in sport mode, I can still track it, but I really want to fix this issue ASAP.
ANY AND ALL COMMENTS ON THIS PROBLEM ARE WELCOME. THANK YOU ALL IN ADVANCE.

[ctrlz]

You did not say which mods you have installed.
What you describe sounds like a major electrical issue, not something that would be caused by a weak/old battery.

My first thought would be water intrusion to the electrical system, and I would check the bottom of the trunk first.
If you have headers, then melted wiring often shows big problems.

[union894]

I'm having same issues with my 16 2ss. No mods. It was running fine then everything shut down, except the engine. Dealership has absolutely no clue.

[WhiteMale]

Ive heard that these cars are extremely sensitive to a bad battery, you should eliminate that, first.