1998 Chevrolet Express Van Owner's Manual - Page 76

Power Door Locks (Option) Press the bottomside of the power door lock switch to lock the doors at once. Child Security Locks Child security locks are located on the passenger side rear door, the side sliding door or the front portion of the 60/40 side swing-out door. With this feature, you can lock these doors so they can't be opened from the inside by passengers. Move the button down to engage the security feature. Move the button up to return the door locks to normal operation. CHILD SECURITY LOCK Printed In U.S.A. When a door is locked, the inside door handle will not work. Rear Cargo Door 2-5