My 99 p71 is having some serious issues. when starting the car i turn my key to the crank position and i lose all power to the car. then after turning it back to off position it gets power back after about ten secs. i have to disconnect the battery multiple times before the car will actually start. any ideas or any related issues? i also replaced the ignition switch thinking that might have been the problem but found out it wasnt. when the electrical is twitching out i can hear the lighting control module tweaking out. please help me out

 

I am thinking possibly bad ground /battery connections..had this happen to me..an aftermarket battery terminal was the culprit..since you said you had to disconect the battery multiple times