ive already looked but im not seeing the plugs for it.

 

They are there. Look under Wiring diagrams- connector end views.

 

It goes into a low-power mode when the vehicle is turned off. There is a small power draw, but I have left it in a vehicle for at least a week without starting it and it still started.

It says it monitors the vehicle battery when parked and will send a notification if the battery voltage goes low. I did get a "battery health" notification once but that was due to a battery that was going bad and wouldn't hold a charge very long.

It's $10 a month for the service and around $80 for the device. I have had it for many years and am happy with it.

Steve

 

Schematics are under : Accessories & equipment - Entertainment Systems

OnStar is called VCIM and Cellular communications and GPS and Mobile Telephone and a few other similar names.
XM is Digital Radio U2K
UQ3 is the amp and Pioneer speaker
UW5 is basic speakers
All of the head units are capable of the XM and OnStar and amplifier.

.UE1 refers to "OnStar installed" not the radio system. You may be looking for the wrong thing.
Here is a pdf of the OnStar schematic: OnStar.pdf
X2 is top center.
Here is a pdf of U2K that includes OnStar to X4: U2K.pdf
Here is a pdf of the various X1 and X2 connectors: Radio X1&X2.pdf
Here is a pdf of all of the VCIM connectors: VCIM connectors.pdf