Battery Draining Fuse 21 HELP

[bimmer206]

I'm stumped. Alternator and voltage regulator tested and are fine, new battery last week, as well. Battery started dying overnight and at work. Through test light and pulling fuses, I have narrowed it down to fuse #21, which according to my Bentley Manual powers:
- Auto-charging flashlight
- Ignition key warning/seatbelt warning
- Interior lights
- Radio/antenna
- Trunk light
- Multifunction clock
- Service interval indicator

Individually, I disconnected the interior lights (glove box and courtesy lights), radio, trunk light, OBC......test light stayed on.

My SI lights stay on in the cluster when the car is OFF. From this thread below where a guy had the same problem as me (which i copied) it seems that the SI board may be sucking the power because the batteries went bad and the car is trying to charge them?

Reference: http://www.m42club.com/forums/showthread.php?t=12048

What is killing my battery????

Edit: My power radio is removed from the car.

[Chuck C]

Your test light is indicating voltage, and what you need to measure is amperage. Get an amp clamp and a good digital volt-ohmeter to check exactly how many milliamps you're drawing, then disconnect one component at a time. From experience, I would guess a light is staying on. I don't think the SI board is the problem, as fuse 21 just supplies memory power to the board. Happy hunting.

[bimmer206]

The SI board is on when the car is not running and off when the car is 0.o

[36brua]

power antenna ? try disconnecting in trunk even though you have pulled the radio

[Chuck C]

Antenna is not on fuse 21.

[bimmer206]

Chuck you seem to know a lot about this problem and your in Seattle, want to give me a hand?

[DÌEGØ]

yeah what chuck said. you need to measure amperage not voltage. my SI service LEDs are ALWAYS they'll draw 12v but not enough amp to drain the battery.....

[evilnickwong]

I have the same problem. I measured current draw on my car, which was gone when I disconnected my cluster.

My SI lights don't stay on (I looked at it in pitch dark and don't see anything), but I've also read that bad batteries can make it constantly try to charge, hence the draw. I have not tried replacing the batteries yet. Right now, I just disconnect the battery whenever I'm not using my car for awhile.

[DÌEGØ]

make sure the battery is clean too. you'd be surprised how much current dirt and crap on a battery will conduct

[bimmer206]

Batteries connection is rock solid, i still have this problem but I've been driving around with fuse 21 pulled. I pulled the cluster to see if this was the SI lights but no luck. Ill measure voltage soon..