just wondering where other owners found the cause of the drain. It seems like a
common problem but no one ever posts their fix.

 

If you KNEW it was the Room fuse, then you could disconnect, one at a time, the items fed by the Room fuse, til the drain stopped. See attached jpg for what gets fed by the Room fuse.

What you do is go to the wiring diagrams. Look page by page at the top of each page where you see the feed lines. Anytime you see a 9 (3) on the B line, that is coming from the ROOM fuse. An example is attached.

 

Thanks again Hailers. Is the EGI part of the ECU? I just replaced the ECU with a used one but I had the drain before that. I thought it was the alternator slacking off but it seems like the problem is back.Once the battery lowers to 12V the alternator belt starts screaching. When I charge it back up it's good for a mile or 2. The alternator is okay.

 

Yes. It goes to the ECU. Small plug. Located on the far left end of that plug. A white/blue wire. It feeds a constant batt voltage to the ECU all day and night long.

It really sounds like your alternator is kaput OR maybe you have the spacer that goes on the long bolt in the wrong place?

I've doubts it's the ECU dragging things down. But you could pull the plug off over night and see if the battery is still up the next morning. Same with the other items that get fed by the Room fuse. But if a light bulb isn't lit up after you turn the key to off, then there's no need to think it's the cause. Common sense thing.

Your alternator or install of the alt seems to be a problem. Or the idler pulley could be the cause of the screeching.

 

I've had the alternator checked and it was fine. When I charge the battery up it will run fine until the volts drop to 12 then the screeching begins. The battery drains overnite. I'll start with the alarm. Thanks again.

 

The screeching is possible the idler pulley the bel.............ooops. No idler pulley for the alternator. My bad. Well, there's something freezing up and causing the belt to screech. Where is the spacer on the alternator? Front or back?

I'd try the Radio next. The plug on it has a Blue/Red wire (L/R)

Maybe the bearings in the alt are freezing up. Then when it cools down, it spins once more. Next time it happens, leave the engine running, lift the hood, reach over and up the throttle linkage and look/see/smell the screeching problem.



The spacer I mentioned determines if the belt is aligned b/t pulleys or not.

 

I've got an S5 which don't have the alternator bushing.The alternator and surrounding area is covered with belt filings. The belt is definitely aligned.
It will run fine after the belt is tightened but within a mile start screaching and burning out the belt.

 

the transmission control unit is drawing power when the car is off. What's with that?

 

Got me. Like the jpg shows, it gets batt pwr 24hrs a day. Much like the ECU does. I know of no document that tells just what it does or how much current it should be drawing with the key off.

All my other jpgs were series four because I didn't know what series you had.

 

Strange, after unplugging and plugging the harness from the control unit the draw is now nomal at .03 but when I turn the lights on or any other accessory the
belt starts screaching.