Grounding I think

So I have a 2013 Tundra that has me baffled, so I left out last Friday at 2 o'clock in the morning hadn't driven far and noticed when I stepped on the brakes everything blinked for a second, didn't think much of it until I put the high beams on and the radio shut off the lights dimmed for a second the tac dropped out and all the warning lights came on and then everything returned to normal I drove 400 miles that day and the problem would just happen every now and then. I took to my Toyota dealership today they put on machine showed no problems the tech even drove it 40 miles and no problem, so I came back home then I went to a meeting tonight and there was the problem again after a 2-hour meeting on the way home everything was normal again any ideas what the problem could be and how do I find it.

 

It sounds like grounding to me as well. A thorough inspection looking for any loose connections or evidence of rodent damage would be my first step. I would document everything I checked. If you find nothing, a dealer or other reputable shop can then try to check things you missed or could not get to, saving you billable hours. I'm sure someone else will have other ideas, and I hope there is something easier to find.

 

these cold temps are killers to battery. A dead cell can be bad for any kind of module to work correctly . Test the battery and clean and check connections . Not denying the ground issue but electrical 101 is to test the power source

 

If your battery is at minimum voltage it will work but at times will dip and spike causing the issues. Just a guess but a bad GND I would think would be a constant problem and not intermittent issues like you are describing. Interested to hear what the problem is