The automatic locking retractor (ALR) is a feature incorporated in the subject vehicle for locking the webbing to properly secure a child safety seat into a vehicle.this PE was opened based on a GM technical service bulletin stating that with certain child safety seats the webbing may not remain locked.there are no complaints in the ODI database and only two complaints to GM.GM's instructions state for the final step in using the webbing lock feature to push and pull the child restraint to be sure it is secure. If the ALR is not locked, the user would be fully aware of this condition prior to completing proper installation of the child safety seat in this vehicle.this investigation did not uncover any complaints of the ALR inadvertently unlocking while the vehicle is in motion.the emergency locking retractor (ELR) feature remains available to lock the retractor in a crash.a safety-related defect has not been identified at this time and further use of Agency resources does not appear to be warranted.accordingly, this investigation is closed.the closing of this investigation does not constitute a finding by NHTSA that no safety-related defect exists.the Agency reserves the right to take further action if warranted by the circumstances.see attached summary for additional information.