The recall covers 2011 to 2014 Jeep Grand Cherokees and Dodge Durangos.
The company said brake booster shields were added as part of a 2014 recall, but a check of warranty claims found that some weren't installed correctly. In those cases, water can cause corrosion or get inside the booster and freeze. That can reduce braking ability, increasing the risk of a crash.
Fiat Chrysler said it knows of one potentially related crash but no injuries.
Timely, incisive articles delivered directly to your inbox.