Security researchers Chris Valasek and Charles Miller performed the hack after spending a year developing the software to hack into a Jeep Cherokee and control the vehicle through its Uconnect media system. Their successful efforts appeared on the Internet and as part of an article in Wired Magazine.

The hackers were able to upload a picture of themselves onto the 8.4 inch touch screen in the Cherokee's dash as well as turn on the radio and blast the volume, turn on the air conditioning and the windshield wipers, spray washer fluid and even turn off the engine all while the vehicle was traveling on the road at 110 kilometers per hour. They were also able, in a parking lot demonstration, to not only unlock the Cherokee, but to also seize control of the steering wheel, when the Jeep was moving in reverse, and disable the breaks.

FCA advised customers to update their software in response, but then changed the advisory to a recall. Chrysler has also initiated increased network level security to block remote access to certain vehicle systems. These measures were tested and put into action on July 23 of this month and don't require customer or dealer action.

Here are the vehicles which are affected by the recall according to Fiat Chrysler's own blog http://blog.fcanorthamerica.com/2015/07/22/unhacking-the-hacked-jeep/

Not all vehicles with 8.4 inch touch screens are affected and the recall is restricted to vehicles in the USA. Customers will receive a USB device and can update the software themselves or they may take their vehicles into the dealership for the update.