DETROIT -- The maker of car radios that friendly hackers exploited to take control of a Jeep Cherokee says its other infotainment systems don't have the same security flaw.

Harman International CEO Dinesh Paliwal says the hackers used a cellular connection to get to the radio. They were able to control critical functions such as brakes and steering.

Paliwal says Harman worked with Fiat Chrysler to fix software bugs that allowed the hackers in and it's co-operating with a government investigation. He says the radios were developed five or more years ago and don't have as much security as current products.

The National Highway Traffic Safety Administration is investigating about 2.8 million Harman radios to see what other automakers use them and whether they are vulnerable.