Ive had a problem for a while now, lets say im just idiling in the driveway at nite with my headlights on ok, i'll open the door, the seat belt retracts automatically & i roll both windows up at the same time.... Now everytime i do this the car starts losing juice like a big electrical drag to where the car starts idiling lower & lower & lower till it almost dies & at the last second the ecu senses a load & adjust its self to stay running then once it does that i can sit there & idil all nite if i wanted too. Does anybody have an idea of what it might be? Car runs great otherwise!!! Could this be battery or altenator maybe a diode in the altenator or something?
Well i take that back it doesnt happen everytime but 8 times out of 10 it does happen like this

 

One way is with a DVOM check base battery voltage or when car has been sitting for a while should be close to 12.6volts.....turn engine on voltage should be 13.5-15 volts rev up to 2000 rpm also look for 13.5-15v (anything higher than 15 volts or lower than 13.5 bad alternator, loose or slipping belt, etc) have someone operate headlights, seat belts, etc voltage should not drop below or get close to base voltage should be a little lower than running voltage. Hope this helps this is a industry standard charging system test.

 

Thanks i'm gonna test it tonite, see what we got