The Mesa has a standard vehicle belt install and I had no issues getting it nice and tight. It incorporates a belt lock-off, like many other infant seat bases. This feature allows you to install the car seat without locking the vehicle belt. The tension indicator which is incorporated into the SMARTsecure system also works with the vehicle belt install. You thread the vehicle belt through the belt path, then under the lock-off, tighten the belt, and close the lock-off. Once you have the vehicle belt tight the indicator window shows green. We still encourage checking the tightness of the seat though. There should be no more than 1″ of movement from side to side or front to back at the belt path.
We have been told by UPPAbaby that if for some reason the base still is not to the desired tightness, the vehicle belt’s locking mechanism can be used while still being routed through the lock-off door.
They have also stated that if you have a convenience button or a sewn in loop on the lap portion of the vehicle belt, you can install without using the lock-off. This button or loop helps the buckle on the vehicle belt remain easily accessible rather than slipping down to the floor of the vehicle for adult passengers, but sometimes cause installation issues with lock-offs.
The lock-off stays closed and the vehicle belt is routed over it but still under the ‘T’ of the lock-off. As with all other installation methods the indicator window will still show green with this install method. Please remember to use the locking mechanism on the vehicle belt when installing using this method.
The Mesa is one of the easiest lower anchor installs I’ve ever done. The SMARTSecure system integrates the ratcheting lower anchor strap. These ratchet straps consist of two independent retractors in the base. The retractors are similar to that found in a vehicle belt retractor. To start the install the lower anchor connector needs to be pulled out of the connector storage compartment on the base, then the orange button is pushed on the top of the base. This button allows you to pull the straps out of the base. The straps need to be pulled as far as possible from out of the base while continuing to push the orange button. The hardest part of the install is that you’ll need to hold the strap so that it doesn’t ratchet back in until the lower anchor connector is connected to the vehicle lower anchor. The push on lower anchor connectors help with this step. Once the connectors are connected, you release the lower anchor strap which ratchets into the base making the base tight without having to pull any lower anchor strap tail as in most car seats. You do this with each side, then push down on the back of the base until the tension indicator turns green. Rocking the base back and forth can help with this step.