GMC Envoy Owner's Manual page 285

The traction control off symbol on the button will come
on under the following conditions:
•
The Traction Assist System is turned off, either by
pressing the on/off button or by turning off the
automatic engagement feature of the TAS.
•
The transmission is in FIRST (1) gear; TAS will not
operate in this gear. This is normal.
•
The vehicle is driven on an extremely rough road.
When the vehicle leaves the rough surface, slows
down or stops, the light will go off and TAS will
be on again. This is normal.
•
A Traction Assist System, Anti-Lock Brake System
or engine-related problem has been detected and
the vehicle needs service.
4-10
When the traction control
off symbol on the button is
on, the TAS is off and will
not limit wheel spin. Adjust
your driving accordingly.
The Traction Assist System, as delivered from the
factory, will automatically come on whenever you start
your vehicle. To limit wheel spin, especially in
slippery road conditions, you should always leave the
system on. But you can turn the TAS off if you ever need
to. You should turn the TAS off if your vehicle ever
gets stuck in sand, mud or snow and rocking the vehicle
is required. See Rocking Your Vehicle to Get It Out
on page 4-44 and If You Are Stuck: In Sand, Mud, Ice
or Snow on page 4-43 for more information.
To turn the system on or off, press the TAS button
located near the shift lever. If you used the button to turn
the system off, the traction control off symbol on the
button will come on and stay on.
You can turn the system back on at any time by
pressing the button again. The traction control off symbol
on the button should go off.