DirtyBomb

seriously weird problems here. 96xj, i parked it last night, no issues. go to leave this morn and my tach is dead. also no signals or brake lights -_- i check fuses, bulbs, all good. this time i decide to replace the flasher for $17. strangely enough, autozone says this flasher i have is not compatible with my truck, but its the same one i had in before and it worked, tridon ep27.
anyway, no change. whats really weird is i can flick the turn signal and the tach works. push the brake pedal and it dies, flip the defrost or ac on and it dies.
i put the new flasher in and pulled the battery cables just to rest everything, and now the tach works, but when i push the brake pedal, it dies.

any ideas?

could moisture have anything to do with it? we've had a few days of rain here and my truck is not sealed very well, being that it is half chopped up