I beleive that we tested the 2005 X5 system with the amp both disconnected and connected.

Since Bob didn't mention the battery trick, I'm not sure where to go with that.

I hope to see the last car we upgraded soon and I will test that theory (at the risk of having to send the car to the dealer for a trouble code reset: )

If any Portland Oregon X5 owners are willing to have me measure their vehicle in the meantime, just contact us at 503.222.1305 or at kenw at avincar.com