Power Amp Draining Battery

I recently came back from a four day trip, and found that my battery was dead. I bought my MY '99 last fall, so, not knowing the whole history of the car, I figured the battery was overdue for replacement. No big deal. A couple of weeks prior to that, I had replaced the CR-220 head unit with a Nakamichi, and kept the factory six channel "hi-fi" amp. I had to fiddle with the wiring a bit, but eventually got it right - at least everything worked... So, daily drivind with new battery, no problems. Fast forward to this past weekend. I was out of town again all week last week, and when I returned, the new battery was drained completely. At that point I started to think it was connected to my radio installation. I check the current draw at the battery with the car off, and sure enough, over 200mA (probably well over, since 200mA the max my digital meter can read) were being drawn. So, I start pulling fuses, and determine that it is the D9 fuse for the hifi power amp circuit. I pulled the head unit out and unplugged all of the power wires, and determined that the power amp is on all the time, independent of the head unit. One way to stop the current flow is to pull the D9 fuse. One other way was to disconnect the black plug from the power amp. So, any ideas what would cause the power amp to be always on? Is it switched on via a relay? that might be fried into the "on" position? If there is no relay, what could it be? Thanks in advance for any suggestions.

My configuration is exactly the same as yours. I had to reverse two power wires. One of them might be the trigger for the amp and it is hooked up wrong. I remember it was a red and an orange I had to swap them in the aftermarket loom. The loom only had 4 wires.

Sometimes, aftermarket head-units have reversed ACC and ON power wires. One could be yellow or red or vice versa.

Thanks for your replies. The power amp is apparantly on (drawing big current), even with the head unit completely disconnected. The only way to shut it off is to disconnect fuse D9. I wired the system so that I would not have to cut any of the stock wiring. To do this, I bought the VW connector for the power socket and the smaller yellow Audi connector for the line out socket. As I think through this some more, it may mean that the VW power connector, which has a blue wire bridging two of the connections may connecting the power amp to the hot lead. I'll have to check this when I get home tonight.

Same harness I used

I feel your pain, as Slick Willie used to say. My new Recaros drained my battery a few weeks ago. I inadvertantly left the fan on while the car sat undriven for 4 days. I was soooooo amused.

My hunch was right, though I'm still not exactly sure why. Just to re-cap, I bought the Metra harness p/n 70-1787, which is sold as an Audi and VW adaptor (but fits the 99-01 MY 996 Beckers perfectly), in order to preserve the stock harness connector. This part is actually two parts, the black connector that goes between the stock harness that goes to socket A on the Becker CR-220 or CDR-220, and a red connector that mates with the harness (yellow connector) that connects to C1 on the stock radio. The black "A" connector basically covers the power and ground for the head unit. But, for some reason is comes with the two blue terminals (A3 and A5) bridged. Everything was wired up correctly, but the power amp was draining my battery with the ignition off. After eliminating everything else as the cause, I cut the blue wire bridge, and that solved the problem. For Porsche, A3 is the telephone mute/clearing function, and A5 is the control output for the automatic aerial/amplifier. For Audi/VW these lead may have some other purpose. Anyway, if you get this socket kit for your 996, be sure to remove the blue bridge wire between A3 and A5. As to why this bridging was causing the amp to draw current when the ignition was off, I'm still baffled.