Cadillac 2003 CTS Owner's Manual page 186

Service Idle Control
A problem with the idle control has occurred when this
message displays. Have your vehicle serviced by your
dealership.
2-118
This symbol appears
with the Service Idle
Control message.
Service Stability Sys Message
Your vehicle may be equipped with a vehicle stability
enhancement system called Stabilitrak.
See "Stabilitrak" in the Index. The Service Stability Sys
message will be displayed if there has been a problem
detected with Stabilitrak (if equipped).
If the Service Stability Sys message comes on while you
are driving, pull off the road as soon as possible and stop
carefully. Try resetting the system by turning the
ignition off then back on. If the Service Stability Sys
message still stays on or comes back on again while you
are driving, your vehicle needs service. Have the
Stabilitrak system inspected as soon as possible.
This symbol appears
with the Service Stability
System message.