The short story version. My sisters 99 v-6 mustang. Her sons installed a aftermarket stereo and then when they got a car so they put the original stereo back into the car. Now the fun starts. Dead battery, wipers don't work, alarm will no longer unlock or lock the doors or work anything, and if you try to start the car the pats blinks the light at you. Car had a blown ignition fuse that got replaced. Car started and drove her to work. Now it is dead. It will crank but no start, with the above syptoms. Is there a ground somewhere in the dash that could have been damaged by the boys?

 

Without knowing more, you could be chasing the issue for awhile.

Is it cranking solid, or slow - like a battery is being drained slowly by an electrical screw up?
Cranks but not having wipers, door locks etc... is a strange mix.

 

If it started fine and got her to work if say the battery has just crapped out. Now why it's crapped out is another issue. Did something have a slow draw? Did the alternator fail to charge it? Are the terminals dirty? Could be a bunch of things.

 

I'd guess the alt is good if it stays running after a jump.

 

So I got it fixed well diagnosed anyway. 4 hours and this is what I found. Battery is bad. Put new battery in it. Found 4 fuses in the wrong holes so stuff was no being turned on. Had to add 2 fuses that were missing from their messing with it the other day. So everything works and the pats light just flashes when you try to start. Have 6 fuses in the cab with no power to them. Finally found the problem after two hours of internet searching. The ccrm (constant control relay module) is having issues. Its on the inside passanger front fender behind air cleaner. Beat it on the car pats light stopped blinking car runs great. Not getting battery power to the dead fuses but enough to run the car. With no electrical schematic I guess I did ok.