Car Seats Series #4 : Harnessing
Estimated reading time: 7 minutes
Learning to use the Car Seat Harness correctly is important because four of the most common car seat mistakes parents make involve the incorrect use of the harness. More about those later…
After selecting the right car seat for your child’s car seat stage (selection) and installing it (direction, location and installation) — and preferably having that installation checked by a certified Child Passenger safety Technician, there is harnessing.
From birth to booster age you are likely using a 5-point harness car seat. This means the car seat harness system contacts your child in five points: both shoulders, both hips and the crotch. These are the strongest points of the body. A 5-point harness spreads the crash force evenly over the child.
First thing first, which direction is your child facing?
Deciding which slot the harness goes through the car seat depends on your child’s height and which direction your child is facing in the car.
If your child is in a rear-facing car seat, the harness strap should be at or below your child’s shoulders. Putting shoulder harnesses too high for rear-facing children has a similar effect as not fully tightening the safety harness itself. Most car collisions happen when the car is moving forward, causing a rear-facing child’s back to be pressed against the seat back of the child restraint seat. This means that a main goal of a rear-facing car seat harness is to keep the child’s body from sliding upwards along the child restraint’s seat back. Every tiny increment of increased distance the child moves exponentially amplifies the forces on the child’s body. The more a child’s body accelerates, the more the child’s head and chest are subjected to increased g-forces both at the beginning of the collision and during deceleration after the collision.
If your child is in a forward-facing car seat, the harness strap should be at or above your child’s shoulders. While forward-facing the crash forces will cause the child’s body to be thrown forward. The harness straps should be positioned at or above the child’s shoulders when forward facing to most effectively decrease the amount of distance the child will travel when propelled forward and to limit the forces on the child’s spine and shoulders.
Make sure the harness straps are both going through the car seat — shell and cover — at the same level and neither strap has any twists in it. When they are twisted the crash force is placed on a smaller area of the body which can cause increased injury.
Once your child is in the car seat.
Pull the harness straps over your child and buckle the harness and close the chest clip.
Pull the harness straps to a snug tightness. This means if you try to pinch the harness horizontally you cannot pinch the material together. This is the “pinch test.”
Move the chest clip to armpit level. (We recommend tightening the straps then moving the clip up to position. If it starts high, you could tighten the straps and pull the clip right into the child’s throat.)
That seems simple enough, right?
Except that as mentioned, harnessing mistakes account for four out of ten of our most common car seat mistakes.
Those mistakes include:
1. Not having the harness straps snug enough.
A large number of parents still leave the harness too loose. At checkups we often hear them say something like, “it seems too tight and uncomfortable.”
A “snug” harness equals “a snug strap should not allow any slack. It lies in a relatively straight line without sagging. It does not press on the child’s flesh or push the child’s body into an unnatural position.” You want the straps to be “as snug as a hug.”
Why is this so important? During a crash the harness straps are holding the child in the car seat. If those straps are too loose, the child will not be properly secured and could even come out of the straps becoming an unrestrained child.
The child should not wear bulky clothing like a puffy winter coat in the car seat harness straps. During a crash the bulky clothing would compress then the straps would be too loose.
Crash testing shows with 3 inches of harness slack, the child’s shoulder can slip out of the harness allowing the child’s head to extend past the car seat and strike the vehicle door in a side-impact crash.
2. The chest clip is not at armpit level.
In many car seats the chest clip is meant to break during a crash, so how can the position be so important? Well, too low and the harness straps may not be positioned correctly on your child’s shoulders, especially if the straps are also too loose. In this case, the clip prevents the straps from separating, ensuring your child is not ejected during a violent crash. Too high and prior to breaking, it could compress on your child’s throat.
3. Harness straps are not properly positioned for the child.
For rear-facing child safety seats, if you are looking at the child sitting in the seat the straps should be going through the safety seat at the slot at or below the child’s shoulder. In other words, you should not be able to see the strap coming out of the seat above the shoulder, it should be hidden beneath the child’s shoulders.
When rear facing in a forward crash — the most common type of crash — the first motion is going to be the top of the child seat rotating down toward vehicle’s floor. If there is enough crash energy, the child’s body is going to try to slide toward the top of the child safety seat. You want the harness straps to be cradling, or at least very close to the child’s shoulder, so that they do not slide “up” into and stop suddenly or even go through the neck opening when they finally hit the misplaced straps.
For forward-facing car seats, the harness straps should go through the safety seat at or above the child’s shoulder. Think about how our seat belt is positioned on us. It anchors above our shoulder so that we lean into it in a forward impact.
Download our report: Common Car Seat Mistakes and How to Fix Them
4. Harness straps are not routed correctly through the car seat.
Why is this so important? The car seat manufacturer crash tested your car seat and meant for the straps to be used in a certain configuration. If you routed the straps incorrectly, it could interfere with the performance of the car seat during a crash. If the car seat harness straps are twisted, they may not distribute the weight correctly and cause injury.
Also remember, to not have anything thicker than sweatshirt material between your child and the car seat harness straps. This includes thick winter coats, blankets and those nice fuzzy, plush car seat covers that have a back section between the baby and car seat.
A note about cleaning car seat harness straps
When the straps need to be cleaned, wipe them with a moist cloth. You can use a baby wipe or a washcloth with a little drop of soap. Do not submerge or wash in the washing machine, this ruins the integrity of the strap. If such a thorough cleaning is necessary, you should replace the straps. Call the manufacturer of the child restraint to get new straps.
Get a visual of car seat safety rules.
We want to know, were you nervous to “over tighten” the car seat harness straps when you first started putting your child in a car seat? Share your comments below.
By Amie Durocher, Creative Director at Safe Ride 4 Kids and certified CPS Tech since 2004
Copyright 2022 Safe Ride 4 Kids. All rights reserved. You may not publish, broadcast, rewrite or redistribute this material without permission. You are welcome to link to Safe Ride 4 Kids or share on social media.
We originally published this post in January 2017. We updated the article for accuracy and comprehensiveness.