Cadillac 2010 STS - Manual (Page 76)

If the child restraint does not have the LATCH system,
you will be using the safety belt to secure the child
restraint in this position. Be sure to follow the
instructions that came with the child restraint. Secure
the child in the child restraint when and as the
instructions say.
If more than one child restraint needs to be installed in
the rear seat, be sure to read Where to Put the
Restraint on page 2‑38.
1. Put the child restraint on the seat.
2. Pick up the latch plate, and run the lap and
shoulder portions of the vehicle's safety belt
through or around the restraint. The child restraint
instructions will show you how.
3. Push the latch plate into the buckle until it clicks.
Position the release button on the buckle so that
the safety belt could be quickly unbuckled if
necessary.
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