The official notice
Defect
Certain vehicles may be equipped with an accessory trailer wiring harness that could fail. Over time, water could leak into the control module and cause a short circuit. If this happens, there could be loss of the trailer lights. Note: This recall affects trailer wiring harness kits that may have been ordered at the time of a vehicle purchase, or purchased separately from a dealer as an aftermarket accessory.
Safety Risk
A loss of trailer lights could make the trailer less visible. In addition, other drivers may not recognize that the vehicle ahead is braking or intends to turn. This could increase the risk of a crash.
Remedy
Kia will notify owners by mail and instruct you to take your vehicle to a dealer to inspect the trailer wiring harness. If the harness is from the lot (batch) affected by this problem, the dealer will replace it. Kia recommends that you should always check to ensure that trailer lights work properly before towing.