2017 Tacoma Transmission/Electrical Problem

Looking for help on a weird problem. Truck had an alternator go bad 6 months ago, radio static every time the brake pedal was pushed after replacement. Assumed the autozone alternator was bad but no other issues so left it. Fast forward to 2 weeks ago, out of town at the parents and the truck transmission gear light on dash and shifter starts flickering which confuses the trans. Shifts in and out of gear at low speeds and only acted ok at highway speed. Got another autozone alternator and same thing happens within a few hours. Hook a volt meter to the truck and voltage is spiking to 19v at idle at random, no shift light craziness. Replaced with a toyota alternator and truck is doing the trans shift light thing again. Low speeds only or pulling a hill at low speeds. No check engine light or stored codes. Any ideas would be appreciated.

 

Rodents perhaps?

 

Maybe. Update from this morning. Cool morning, went to start the truck and it wouldn't recognize what gear trans was in or shift until the engine had heated up.

 

I like the "rodents" idea. (Don't) Ask me how I know.

 

Check for a bad ground

 

Does anyone have all the ground locations?