See also:

Blank Display
This display shows no information. ...

Tachometer
The tachometer displays the engine speed in revolutions per minute (rpm). For a description of how Grade Braking affects vehicle speed while the Tow/Haul Mode is activated, see Tow/Haul Mode on page 9 ...

Add-on Electrical Equipment
The OnStar system is integrated into the electrical architecture of the vehicle. Do not add any electrical equipment. See Add-On Electrical Equipment on page 9‑64. Added electrical equipment ...