The government's automobile safety agency is investigating the anti-lock braking systems of 1991 Chrysler Corp. minivans after receiving three complaints that leaks were causing brake failures.

The National Highway Traffic Safety Administration on Wednesday also reported stepped-up probes of corroding door hinges on Isuzu Troopers, sticking throttles on this year's Ford Explorer and speed control failure in the 1991 Honda Acura Integra.The Chrysler Town and Country, Dodge Caravan and Plymouth Voyager minivans are the targets of the braking investigation, the agency said. An estimated 300,000 have been sold, but Chrysler spokesman Tom Jakobowski said "substantially fewer" have the optional anti-lock brakes. He could not give an exact number.

The investigation is in the initial stage, known as a preliminary evaluation, which involves mostly paperwork. If evidence of a hazardous, widespread defect is found, a recall could be ordered.