Automatic Transmission Operation - GMC 2010 T-Series Owner's Manual

Diesel Engine Exhaust Brake
The exhaust brake is used to help slow the vehicle and
may assist the vehicle's foundation brakes. The use of
the exhaust brake will assist the braking of the vehicle
and prolong the life of the foundation brake lining
material.
Push the bottom of the button to turn the exhaust brake
on. When you push the top of the switch, the exhaust
brake will turn off.
There is an indicator light on the instrument panel
similar to the symbol on the switch, that will come on
when the exhaust brake is active. See Exhaust Brake
Indicator Light on page 3 35 for more information.
2-16
The exhaust brake button
is located in the
instrument panel.
When using the exhaust brake, the proper gear range
selection is important. The exhaust brake will be most
effective if the gear range selected is the lowest
possible range that does not allow the engine rpm to
exceed 2500 rpm.
If you have an automatic transmission and press this
button, the transmission will downshift to a factory
default setting of 4 (Fourth) gear. To change the default
setting, or for more information on factory default
settings, contact your dealer/retailer for assistance.
The accelerator and clutch pedals, on a manual
transmission, must be released in order for the exhaust
brake to engage.

Automatic Transmission Operation

This part of the manual covers the basics of automatic
transmissions. With these transmissions, you will find
®
an Allison Transmission Operator's Manual in the
vehicle that goes into more detail. On the headliner, in
front of and above the driver, or in some other place
near the driver, you will see a label that describes
important operating facts about the automatic
transmission in the vehicle. Make sure you follow the
instructions on this label.