The car seat base should be installed without the car seat attached. Follow instructions in the Rotating and Removing the Car Seat from the Car Seat Base to remove the car seat from the car seat base.
Check that the car seat base StrongArm is set to zero. If not, turn the StrongArm knob counterclockwise until the zero line is visible.
If the LATCH/UAS belt is routed through the belt guides, remove from belt guides. (Note: The belt is permanently routed behind the lockoff clamp). Store the LATCH/UAS connectors in their storage location when they are not in use. Each connector will click securely into its own storage slot.
If the vehicle seat back is adjustable, lock the vehicle seat back into the upright position.
Center the car seat base on the vehicle seat, making sure the areas under and behind the car seat base are clear of obstructions.
Check that car seat base is level by looking at the level indicator. The window in the level indicator must be green. If red appears in the window, try any of the following:
Remove the car seat base. Position a rolled towel under the car seat base, making sure the front of the car seat base contacts the vehicle seat. The towel should be compressed as the StrongArm tightens the car seat base into place.
Install the car seat base in a different vehicle seating position.
The lap-shoulder vehicle belt must be secured in place by the lock-off clamp. To secure the belt in place:
Open the lock-off clamp.
Thread the lap-shoulder vehicle belt through the belt guides and the lock-off clamp.
Buckle the lap-shoulder vehicle belt
Make sure the belt is not twisted and that both belts lie flat across the belt path and the open lock-off clamp.
Pull on the shoulder portion of the vehicle seat belt to tighten the lap portion on the belt path.
While holding the shoulder portion of the vehicle seat belt tight, position the lap-shoulder belt in the lock-off clamp. Secure the lock-off clamp firmly upon both belts by flipping the top closure down into place
Turn the StrongArm knob at the front of the car seat base clockwise to activate the StrongArm mechanism.
Each installation varies slightly, but typically the knob can turn 10 full revolutions. After 10 full revolutions, check the car seat base for a tight installation. You know that you have reached the optimal tightness setting when you grasp with one hand and pull on the belt guides and the car seat base upright does not move more than 2.5 cm (1 in) in any direction.