Stereo & Electronics - my trans. temp guage seams to peg if there's a wiring fault

do'es this sound farminarl first time I noticed the guage peg I had a power & ground touching from my radar detecter also had SES light car ran sluggish and was dumping fuel.

now after amp & sub install same thing this morning trans. guage going real hot & car sluggish.

Do'es the PCM act like this normaly untill it acepts the new stuff hooked up?

& why are wiring faults being transmitted though the trans. guage? is it because it's sender is plugged into a diagnostic port used for testing trans?

Thanks