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Ford Hybrid Brakes Being Fixed, Magazine Says

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Ford Hybrid Brakes Being Fixed, Magazine Says

By Ward’s Staff, Feb 4, 2010 5:00 PM

Ford Motor Co.’s ’10 Ford Fusion and Mercury Milan hybrid-electric sedans have a technical bulletin out to fix the brake-software system on 18,000 models sold prior to Oct. 17, 2009.

Consumer Reports magazine made the issue known in a press release today, saying it experienced a failure of its Fusion Hybrid tester’s brake-by-wire system, which may be the result of electronic interference.

Toyota Motor Corp.’s Prius hybrid is under government investigation for loss of braking power, which Toyota says is to blame on overly sensitive antilock brakes.

Lawsuits allege brake failure in other Toyota models and call into question whether electronic interference could be causing that issue as well.

“As one of our senior engineers slowed for a stop sign at the turnoff to our test facility…the brake pedal went unexpectedly further down than normal, but the car barely slowed,” Consumer Reports says as of the Fusion Hybrid.

The magazine adds the engineer “zoomed through the turn, with brake-system warning lights illuminated on the dash,” and the car “more or less coasted to a stop” with minimal brake feel.

Turning off the engine and restarting the car resulted in normal operation.

Consumer Reports staff took the car to a Ford dealership, which told them a technical service bulletin had been issued describing “a situation much less scary-sounding than what we experienced.”

The bulletin notes electrical interference may cause the car’s brake-by-wire module to temporarily turn off. If this were to occur, hydraulic braking would activate but the pedal would drop by 1 in. (2.5 cm).

“Ford engineering representatives explained that the software threshold for establishing a fault in the regenerative brake system was set too sensitively, causing the system to transition to conventional brakes when it was not necessary,” the magazine says.

Consumer Reports says it has found five similar cases and is advising Fusion and Milan Hybrid owners to have their brake systems’ software upgraded if they own an affected vehicle.

Ford issued a statement to the magazine, saying it knows of no injuries relating to the defect.

The auto maker believes the switch from regenerative braking to conventional hydraulic braking “may initially (make drivers) perceive the condition as loss of brakes, even though the vehicle has full braking capability. When this occurs, our system maintains full conventional brakes and full ABS (antilock) function.”



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