GMC Sierra 2008 Owner's Manual page 379

The ITBC system can only be used with trailers with
electric brakes.
CAUTION:
{
Connecting a trailer that is not compatible with
the ITBC system may result in reduced or
complete loss of trailer braking. There may be
an increase in stopping distance or trailer
instability which could result in personal injury
or damage to your vehicle, trailer, or other
property. An aftermarket controller may be
available for use with trailers with surge, air or
electric-over-hydraulic trailer brake systems.
To determine the type of brakes on your trailer
and the availability of controllers, check with
your trailer manufacturer or dealer.
When trailering, make sure of the following:
•
The ITBC system is used only with trailers that are
equipped with electric brakes.
•
All applicable local and federal laws and regulations
are followed.
•
All electrical and mechanical connections to the
trailer are made correctly.
•
The trailer's brakes are in proper working condition.
•
The trailer and vehicle are properly loaded for
the towing condition.
The ITBC system is a factory installed item.
Out-of-factory installation of this system should
not be attempted. GM is not responsible for
warranty or performance of the system resulting
from out-of-factory installation.
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