All seat belts are designed to lock in a crash. Some seat belts will only lock at the time of a crash. Others can be locked manually.

It is safest to secure a harnessed child car seat by a locked seat belt whenever possible. This keeps the child seat tight and in the correct position while driving. With an ‘unlocked’ seat belt, it is possible that the child car seat could move and be out of position at the time of the crash.

Some child car seats come with a built-in locking mechanism. The seat belt is pulled tight and then locked in place.

Many child car seats do not have a built-in locking mechanism. For these seats, you must find out if the seat belt can be locked manually.

Locking Mechanisms

Most, but not all, seat belts can be locked manually. The locking mechanism is either in the ‘latchplate’ or in the ‘retractor’ of the seat belt, never both.

Latchplate

The latchplate is the metal tongue that clicks into the buckle:

A locking latchplate is one that locks the seat belt in place when pulled tight.
Some locking latchplates have a metal bar at the back:

Other locking latchplates have a moving metal or plastic piece:

A switchable latchplate is one that can be locked by a button on the back of the latchplate:

If your vehicle’s seat belt has locking latchplates then you do not have to do anything more than tighten the seat belt when installing a child seat. The latchplate will lock the child seat in place.

 

Retractor

Most lap/shoulder seat belts, and some lap only belts, have a retractor. A retractor is a mechanism where the excess seat belt webbing is stored and pulled out from. All retractors will lock in a crash or sudden stop; but not all can be manually locked.

To assess whether the retractor can be locked manually, gently pull the seat belt all the way out to the end. It should not be tugged sharply.

Once the seat belt is all the way out, allow it to retract a short distance. If there is a clicking sound as it retracts, then the retractor is now manually locked. If there is no clicking sound, gently pull the seat belt out again. If the seat belt will not pull out any further, then the retractor has been locked.

If the retractor cannot be manually locked, there will be no clicking sound, and the seat belt webbing will easily move back and forth in the retractor.

If your vehicle has no locking latchplates and the retractor cannot be locked, you will need to use a locking clip to install your child seat.