i own a 99 yukon slt. i have had it for about 4 years now. it has always had a battery over nite draining issue.i have put sevaral new batterys in it. and they dont lst long if i dont unhook the battery.everything works and no interior lights stay on.no underhood light problem.no hung relays. no noises after key turned off. when u take the battery cable loose and brush against the batt terminal wow what a spark.i know it should have a slight spark becuase of computer and radio and so on memeory issues.this is different i took the computer all the way out of the truck and it still jumps enuff spark to set off a stick of dynomite.under the hood i have taken all the relays out of the relay fuse block. i have three 50 { even if they are put in one at a time} amp fuses that will let the battery create this extreme battery spark issue.i can put all others in and leave 3 them out and i no longer get this huge spark. if i can find out what is on these 3 circuits then i should be able to find the culprit or culprits.how can i find out what these 3 circuits supply juice to? last i have tried to include all info i can not just to fill up space. in hopes this is something familar to someone. p.s. i have seen on another site that the body control modual has had an issue like this on trucks like mine. ok! where is it located i am having trouble finding it. i have a 99 villager ripped up in the drive way right now. my wife needs to be able to have a dependable way to work so i am trying to fix to different vehicals at once.:screwy: this is me! help and thanks!!!!!!!!!!!

i own a 99 yukon slt. i have had it for about 4 years now. it has always had a battery over nite draining issue.i have put sevaral new batterys in it. and they dont lst long if i dont unhook the battery.everything works and no interior lights stay on.no underhood light problem.no hung relays. no noises after key turned off. when u take the battery cable loose and brush against the batt terminal wow what a spark.i know it should have a slight spark becuase of computer and radio and so on memeory issues.this is different i took the computer all the way out of the truck and it still jumps enuff spark to set off a stick of dynomite.under the hood i have taken all the relays out of the relay fuse block. i have three 50 { even if they are put in one at a time} amp fuses that will let the battery create this extreme battery spark issue.i can put all others in and leave 3 them out and i no longer get this huge spark. if i can find out what is on these 3 circuits then i should be able to find the culprit or culprits.how can i find out what these 3 circuits supply juice to? last i have tried to include all info i can not just to fill up space. in hopes this is something familar to someone. p.s. i have seen on another site that the body control modual has had an issue like this on trucks like mine. ok! where is it located i am having trouble finding it. i have a 99 villager ripped up in the drive way right now. my wife needs to be able to have a dependable way to work so i am trying to fix to different vehicals at once.:screwy: this is me! help and thanks!!!!!!!!!!!

Are the three 50A fuses in of the maxi fuse style?size?
You should be able to determine these fuses underneath the fuse cover on the diagram, otherwise the owners manual I would think. Almost sounds like a grounding issue.