GMC Envoy Owner's Manual page 209

Radio Display
Message
XM Locked
Radio ID
Unknown
Chk XMRcvr
3-74
XM™ Radio Messages (cont'd)
Condition
Theft lock active
Radio ID label
(channel 0)
Radio ID not known
(should only be if
hardware failure)
Hardware failure
Action Required
The XM receiver in the vehicle may have previously been
in another vehicle. For security purposes, XM receivers
cannot be swapped between vehicles. If this message is
received after having your vehicle serviced, check with
your GM dealer.
If tuned to channel 0, this message will alternate with the
XM Radio 8 digit radio ID label. This label is needed to
activate the service.
If this message is received when tuned to channel 0, there
may be a receiver fault. Consult with your GM dealer.
If this message does not clear within a short period of time,
the receiver may have a fault. Consult with your
GM dealer.