Cadillac 2011 STS Owner's Manual page 390

Your vehicle has a remote negative ( ) ground
location, as shown in the illustration. It is located
on the passenger side front shock tower. See
You should always use this remote ground
location, instead of the terminal on the battery.
6-40
An electric fan can start up even when the engine
is not running and can injure you. Keep hands,
clothing and tools away from any underhood
electric fan.
.