The Ford announcement came as Consumer Reports said one of its engineers ran a stop sign in a residential area when the brake pedal on a Fusion hybrid sank further than normal and warning lights lit up the dashboard. The car coasted to a stop with minimal brake feel, Consumer Reports said.

Ford said a software glitch on Ford Fusion and Mercury Milan hybrids built on or before October 17 could cause drivers to perceive a loss of braking as the car shifts unnecessarily from regenerative braking into the conventional mode.

The automaker said it had received a handful of reports about the issue. It had heard reports of one minor accident, but no injuries as a result, a spokesman said.

Ford said it would upgrade the software on the vehicles and notify customers by mail that the fix is available at dealerships.

Jeff Bartlett, Consumer Reports' deputy editor for online autos, said one of the magazine's most experienced test drivers braked while approaching a curve in a Fusion hybrid last month, and the brake pedal dropped about an inch.

"They didn't react the way he expected," Bartlett said. "He perceived it to be a brake failure of some kind."

The driver coasted to a stop and shut off the engine, and when he restarted it, the brakes worked normally, Bartlett said.

Consumer Reports notified Ford, which responded quickly to evaluate the problem, Bartlett said.

Here's what happened:
As one of our senior engineers slowed for a stop sign at the turnoff to our test facility in East Haddam, Connecticut, the brake pedal went unexpectedly further down than normal but the car barely slowed. He zoomed through the turn, with brake-system warning lights illuminated on the dash. The car more or less coasted to a stop, with what our engineer described as minimal brake feel.

After switching off the engine and then restarting it, everything returned to normal—no warning lights and full braking capability. We then took the car to our local Ford dealership, where the service manager told us that a Technical Service Bulletin covered this problem.



The bulletin in question, coded TSB-09-22-11, described a situation much less scary-sounding than what we experienced. To paraphrase, it said that electronic interference might cause the electronic brake-by-wire module to switch itself off temporarily. If that happened, the braking system would revert to a backup conventional hydraulic mode that preserved braking capability, but the pedal will drop over an inch. When the engine is restarted, the electronic braking system would resume