GM Service Manual Online
For 1990-2009 cars only

At times, the position of the vehicle on the map may be inaccurate due to one or more of the following reasons:

    â€¢ The road system has changed.
    â€¢ The vehicle is traveling on slippery road surfaces such as sand, gravel, and/or snow.
    â€¢ The vehicle is being driven on winding roads.
    â€¢ The vehicle is being driven on a long straight road.
    â€¢ The vehicle is approaching a tall building or a large vehicle.
    â€¢ The surface streets run parallel to a freeway.
    â€¢ The vehicle has just been transferred by a vehicle carrier or a ferry.
    â€¢ The current position calibration is set incorrectly.
    â€¢ The vehicle is being driven at high speeds.
    â€¢ The vehicle is repeating a change of direction by going forward and backward, or turning on a turn table in a parking lot.
    â€¢ The vehicle is entering and/or exiting a parking lot or garage with a roof.
    â€¢ The vehicle has a roof carrier, ski, or bike rack installed on it.
    â€¢ The vehicle has tire chains on it.
    â€¢ The tires have been replaced.
    â€¢ The tire pressure is incorrect.
    â€¢ The tires are worn.
    â€¢ The battery is disconnected.
    â€¢ The vehicle is driven in heavy traffic where driving is at low speeds and the vehicle is stopped and started repeatedly.