GM Service Manual Online
For 1990-2009 cars only

Inappropriate route guidance may occur under one of the following conditions:

    â€¢ When the vehicle did not turn onto the road indicated by the system,
    â€¢ when route guidance is not available for the next right or left turn,
    â€¢ when the route may not be changed during automatic rerouting,
    â€¢ when there is no route guidance because of a turn at an intersection,
    â€¢ when plural names of places are displayed,
    â€¢ when a delay in automatic rerouting occurs because of high speed driving,
    â€¢ when automatic rerouting displays a route returning to a set waypoint which was missed originally,
    â€¢ when the route prohibits the entry of a vehicle due to a regulation by time or season or any other regulation which may be given,
    â€¢ when a route cannot be found, or
    â€¢ when the route to the destination is not shown because of recently changed or unlisted roads on the DVD.