WARNING: This page is about a different car, the 2003 BMW X5, 2002 BMW X5, 2001 BMW X5, and 2000 BMW X5. However, it is still accessible from the selected car via links, so may be relevant.
64 12 ELECTRIC AUXILIARY HEATER TIGHTENING SPECIFICATION
Type
thread
tightening specification
Measure
1AZ Battery positive and negative leads to auxiliary heater