Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
kidding aside, yes please maintain the battery state of charge while you're looking for the draw. It may be quite elusive so you don't want the battery to go dead on you.
Oh I know where THAT draw is am I'm not willing to dig that deep , tear things apart etc. that kind of digging never goes back right, for me. No I've got the P0758, 1860,0740,0758 crying blues.