If your talking about the booster seat without a back then NO, It is not safe for the child to ride with only a lap belt.
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yes theiris no reason to wear a seat belt if your i n the back
remove the seat to access screws
If there is a seat and a seat belt, yes.
No, it can open normally
Under the rear seat. Open the rear from the rear. Reach in from the middle back of the seat between the two seat belt latches and pull it up.
No.
I can assume that you are talkin about centre belt cause they seem to be a big problem. First of all before you go there , there is a cable that runs from the seat belt unit to the catch that your seat clips into when you have laid it down. You will probably find that the seat catch is not engaged properly which stops a cable from retracting and allowing the seat belt mechanism to release. Try lubricating the latch at the rear of the seat and also slamming. This is a safety device so if your seat is not clipped in properly you cannot pull out seat belt. If this doesn't work - Unclip the the rear protector on the rear of your seat and you will see along the edge of the seat near the bottom ,where you undo the fabric from the seat . Fold the fabric at the top away after unclipping the plastic insert were the belt goes into the seat, You will see some screws holding a steel plate over the belt. Remove the plate - Look on the back of the seat on the steel part and there is a bolt holding seat belt in place , Undo this and abstract seat belt from between foam and release cable from seat belt..
In states with seatbelt laws, there is no age at which you can ride in the vehicle without wearing a seatbelt, front or back. All passengers are required to be buckled up. But in some states ,like Michigan, the age to not wear a seat belt is 16 and only in the back seat
Its shouldn't be dangerous if the child is in the backseat with a seat belt, or if the child is of correct age for safety restrictions, in the front seat with a seat belt. Make sure the child isn't taking of his/her seat belt and/or leaning out of the car.
ANY frayed seat belt MUST be replaced. Fraying, cuts, or any other damage can and DOES make a seat belt fail. Think about this for a moment. $30 or so, OR your life..