blackliststang

so I swaped ecu pats motor harness out of a 2000 mustang gt into a 2002 mustang gt it runs and drives great but I seem to be having problem with my charging system I used the battery out of my 02 and it fired right up but now it seems like right after I shut off the car the battery dies in a matter of minutes could there be a electrical draw some where or is my battery shot and wont hold a charge I tested to day with multimeter while car was running 12.85 fluxing just put in new alt

99GTvert

How old is the battery? And do you possibly have the radio on when turning off the car and is there a subwoofer/amp?

blackliststang

stock mach 460 sound system everything seems to be shut off. ive tried two batterys so far. when I turn the key to the on postion the rear defrost light stays on I pulled the fuse and the wiring to window thinking that might be where the draw is and still the same thing happens

blackliststang

just bought a new battery drained in a number of hrs

cominus

12.8 is low i think, shouldn't it be at least 13 min? I know 99-00 had a different charging system but that could have been just for the v6s.

blackliststang

i just bought a new battery today died in a matter of hrs when sitting im guessing i have something drawing ppower

fastbackford351

Yeah, I'd say so. Sounds like something BIG is drawing it down.

blackliststang

found that my rear defroster is consistently on is there a fuse to pull for this I pulled the fuse for the defogger switch/ac clutch

fastbackford351

Those are two 'nice to have' pieces of kit but that shouldn't be too tough to figure out.