Jeep Grand Cherokee 2016 Owner's Manual page 604

602 STARTING AND OPERATING
• Do not interconnect the hydraulic brake system or
vacuum system of your vehicle with that of the trailer.
This could cause inadequate braking and possible
personal injury.
• An electronically actuated trailer brake controller is
required when towing a trailer with electronically
actuated brakes. When towing a trailer equipped with
a hydraulic surge actuated brake system, an electronic
brake controller is not required.
• Trailer brakes are recommended for trailers over
1,000 lbs (453 kg) and required for trailers in excess of
1,653 lbs (749 kg).
Towing Requirements — Trailer Lights And Wiring
Whenever you pull a trailer, regardless of the trailer size,
stoplights and turn signals on the trailer are required for
motoring safety.
The Trailer Tow Package may include a four- and seven-
pin wiring harness. Use a factory approved trailer har-
ness and connector.
NOTE: Do not cut or splice wiring into the vehicles
wiring harness.
The electrical connections are all complete to the vehicle
but you must mate the harness to a trailer connector.
Refer to the following illustrations.