Install a Chicco KeyFit 35 infant car seat base
The Chicco KeyFit 35 is a rear-facing infant car seat made up of a carrier and a base that stays in the vehicle. You install the base once, then click the carrier in and out of it. The base can be secured in one of two ways: with the vehicle's lower anchors (part of the LATCH system, short for Lower Anchors and Tethers for Children) or with the vehicle's seat belt. Either method is acceptable when done correctly. The right choice is whichever gives a tight, level installation in your specific vehicle seating position.
The short answer
Place the base rear-facing on a back seat. Attach it with either the lower anchor connectors or the vehicle seat belt, but not both unless the Chicco manual for your seat explicitly allows it. Adjust the base's recline until the level indicator shows the correct angle. Tighten the base until it moves less than about one inch side to side or front to back when tested at the belt path. Then click the carrier into the base and pull up on it to confirm it is latched.
Two documents decide the details: the Chicco instruction manual that came with your seat and your vehicle owner's manual. This article does not cover specifications, weight limits or design changes for particular production years of the KeyFit 35, because no verified details of that kind were available. Where this guide and your manuals differ, follow the manuals.
Before you start
Read the Chicco manual for your seat and check the labels on the base and carrier, since instructions can change between production runs. Check your vehicle owner's manual to find out which seating positions have lower anchors and which allow a child seat. Never install a rear-facing seat in front of an active frontal airbag. The back seat is the recommended location. Check the vehicle manual for any lower anchor weight limit. Past that limit, a seat belt installation is required.
Installing with the lower anchors
Find the lower anchor bars in the gap between the vehicle seat cushion and seatback. Set the base rear-facing on the vehicle seat and route the base's lower anchor strap as the Chicco manual shows. Attach each connector to an anchor bar and confirm each one has clicked or locked. Press down firmly on the base while pulling the strap tight to remove the slack. Check the level indicator and adjust the base's recline if it is not in the correct range.
Installing with the vehicle seat belt
Store the lower anchor connectors as the Chicco manual directs so they do not interfere with the seat belt. Route the lap and shoulder belt through the base's marked belt path and buckle it. Lock the belt using the base's belt lock-off, if your base has one, or the vehicle's locking retractor. The manual specifies which to use. Press down on the base while removing all slack from the belt, then confirm the belt stays locked. Check the level indicator and adjust the recline as needed.
Checking the installation
Grip the base at the belt path, where the anchor strap or seat belt passes through it, and push side to side and front to back. Movement of less than about one inch is the commonly used benchmark for a tight installation. Movement at the far end of the base does not count. Next, confirm the level indicator still reads correctly, because tightening can change the angle. Finally, click the carrier into the base and pull up on the handle to make sure it is locked in place.
When to get help
Some vehicles have sloped seats, hard-to-reach anchors or seat belts that are difficult to lock, and these can make a correct installation hard to achieve. If you cannot get the base level and tight, or you are unsure which method suits your vehicle, have a certified Child Passenger Safety Technician check it. These technicians are trained to inspect installations, and checks are often free in the US. Contacting Chicco's customer support with your seat's model number and manufacture date is also a reliable way to confirm instructions for your exact seat.
