I have a 98 A6 and the battery continues to drain down. Had the battery load tested and its fine, the alt is charging out around 13.7-13.9 . When I disconnect the neg side cable from battery and measure the amps being drawn with key off there is about 2 amps between the neg post and the neg cable. So there is something that is drawing the current and draining the battery.

On the positive terminal there is the main red cable and then a smaller one that mounts via the small lug on the side of the terminal. When I disconnect the smaller wire and measure between it and the positive post I get the same reading of 2 amps. With this wire disconnected , and measureing back on the neg side for amps it is almost zero. So I'm sure whatever is on the other end of this wire is the problem. My guess is its either the alternator or the starter. It was late tonight when I found this and I didnt have time to trace the wire. When I disconnect the small red wire there is a faint clicking sound down below where I think the starter would be located. Also, it puts off a good spark when I touch it back to its connector lug.

Could someone please tell me what this wire goes to?

Thanks
Rick

 

It usually goes to the starter's solenoid.
You may have a short or the wire started to rot out and it hangs on by a few threads.