Chevrolet Silverado 2007 Owner's Manual page 124

Once two remote starts, or a single remote start
with one time extension has been done, the
vehicle must be started with the key.
After the key is removed from the ignition, the
vehicle can be remote started again.
The vehicle cannot be remote started if the key
is in the ignition, the hood is not closed, or if there
is an emission control system malfunction.
Also, the engine will turn off during a remote
vehicle start if the coolant temperature gets too
high or if the oil pressure gets low.
Vehicles that have the remote vehicle start
feature are shipped from the factory with the
remote vehicle start system enabled. The system
may be enabled or disabled through the DIC.
See "REMOTE START" under DIC Vehicle
Customization (With DIC Buttons) on page 295
for additional information. If your vehicle does not
have DIC buttons, see your dealer to enable or
disable the remote vehicle start system.
124
Remote Start Ready
If your vehicle does not have the remote vehicle
start feature, it may have the remote start ready
feature. This feature allows your dealer to add the
manufacturer's remote vehicle start feature.
If your vehicle has the remote start ready feature,
your RKE transmitter will have extended range
that will allow you to lock or unlock your vehicle
from approximately 197 feet (60 m) away.
See your dealer if you would like to add the
manufacturer's remote vehicle start feature to
your vehicle.