Cadillac ESCALADE EXT 2005 Owner's Manual page 298

Four-Wire Harness Adapter
Use this adapter to connect a standard four-way
round pin connector to the seven-wire harness on
your vehicle.
4-62
This adapter may be
included with your vehicle
as part of the heavy-duty
trailer wiring package.
Connect the adapter with the tab pointing up. The flip
cap on the vehicle's seven-wire harness will lock
onto the tab and help hold the adapter in place. Plug
the four-way round pin connector onto the adapter.