Diagnostics
OnStar Vehicle Diagnostics will
perform a vehicle check every
month. It will check the engine,
transmission, antilock brakes, and
major vehicle systems. It also
checks the tire pressures, if the
vehicle is equipped with the Tire
Pressure Monitoring System. If a
diagnostics check is needed
between e-mails, push 
, and
an Advisor can run a check.
See also:
Compass Variance (Zone) Procedure
1. Do not set the compass zone
when the vehicle is moving.
On an automatic transmission
vehicle, only set it when the
vehicle is in P (Park). On a
manual transmission vehicle,
only set it w ...
Driving on Snow or Ice
Drive carefully when there is snow or ice between the tires and the road,
creating less traction or grip. Wet ice can occur at about 0°C (32°F) when
freezing rain begins to fall, resulting in even l ...
When to Check Lubricant
It is not necessary to regularly check rear axle fluid unless there is a leak
suspected or an unusual noise is heard. A fluid loss could indicate a problem. Have
it inspected and repaired.
All ax ...