Guidance summary
Keep trailer connections and parking brakes distinct
This reviewed summary is linked to the question. It does not change the saved answer or score.
Read the reviewed summary
The emergency or supply airline is red; the service airline is yellow. Apply the trailer parking brake and follow the prescribed coupling procedure before handling connections. Do not rely on disconnecting the red airline to park a trailer. Check the combination’s air and electrical services before use.
Source: Keep trailer connections and parking brakes distinct
This reviewed summary is available here without another request. The full source opens in a new tab and needs a connection.