Working on my brother's S4. Ever since he go it, 2 years ago, it alway had a drain that would drain the battery in a few days.

Today I want to start testing the fuses to see where the problem is but would like to know what is expected and what isn't.

Any help woud be appreciated.

 

The procedure is to hook up a multimeter between the negative battery pole and the groundstrap or between the groundstrap and the body, set the multimeter to ohms, close all doors, and watch the multimeter. Then pull each fuse in turn until the main drain is identified. Go from there. I think an acceptable drain is about 30 milli ohm.

 

The useful range here for testing is probably the 200mA range (start higher) for this range you need a way to ensure the interior lights are off - or you will blow the DMM's fuse.

Target is approx 15-25mA - anything below about 50mA is probably livable...

Alan

 

Watch the alarm system and don't have the hood open. I did the same diagnostic with a multimeter, and had all the door activated lights off so I could open the doors, but didn't know that if the hood is open the alarm circuit draws current. When I unplugged a green VW electric connector behind the CE that connects to the hood switch the draw was reduced by about 30mA.

 

to see if the door edge light go off roll down the windows then open the door look for the light then close the door see if the lights go off, it may take up to a minute

 

Baseline drain should be 30ma. I've encountered drains of 200-300ma from bad window motor, bad window/sunroof controller, short in sunroof wires, lumbar motor that needed just to be run a few times, and a bunch of things I can't remember now. I had one car where I got things down to 50ma and to get the remaining 20ma would have required tearing a lot of things apart to get to the circuit involved, so I accepted that as good enough.

 

Thanks!