(c)  2009 TheDetroitBureau.com

(The following story has been revised due to breaking news of the Toyota Prius recall. Click Here for that story)

Most observers anticipate a recall of the 2010 Toyota Prius to solve brake problems, but could earlier models face similar action?

How far back do potential braking problems with the Toyota Prius – the world’s most popular hybrid and the best-selling car of all types in Japan – go?  Research by TheDetroitBureau.com suggests the answer is much further than initially believed, and could involve vehicles dating back to the 2005 model-year or even earlier.

After initially downplaying complaints by owners that 2010 Prius brakes could release unexpectedly, the troubled Japanese manufacturer’s CEO Akio Toyoda admitted the maker must “face up to facts,”  and recall 430,000 vehicles, including not only its best-selling hybrid but also the Lexus HS250h, a luxury model using essentially the same technology.

But even as Toyota prepares for another embarrassing recall, an investigation by TheDetroitBureau.com finds that complaints about the hybrid’s brakes and other traction systems may extend back well before the launch of the third-generation Prius, last spring.  This magazine’s reporting team went into the extensive National Highway Traffic Safety Administration files for the Prius and found hundreds of customer complaints either directly detailing problems with Prius brakes prior to the 2010 model-year, or outlining compound issues that appear to involve both brakes and accelerator issues.

And that’s on top of a series of other problems, such as sudden headlight failures and unexpected powertrain shutdowns, that have been identified with the vehicle, which has become a favorite for both environmentally-minded and high-tech-oriented buyers in the U.S. and abroad. (Click Here for more on that story.)

Observers suggest a consistency to the reported Prius issues, in that most seem directly linked to the vehicle’s numerous electronics systems – a fact one of the nation’s best-known “geeks,” Apple co-founder Steve “Woz” Wozniak, pointed out earlier in the week when he told various news media his car would “go wild,” at times due to an apparent glitch with its cruise control system.  And while both safety experts and Toyota officials alike have registered frustration at trying to reproduce such problems, Wozniak said he could make his Prius act up at will.

TheDetroitBureau.com first reported problems with the 2010 Prius brakes on December 24, 2009.  Owners like New York City’s Robert Becker have complained repeatedly – both the Toyota and to the National Highway Traffic Safety Administration – that the brakes have an unsettling tendency to release for up to a second when the vehicle hits a pothole, bump or icy patch.

Toyota now blames the “aggressive” programming of the 2010 Prius’s anti-lock brake system, or ABS, which is designed to prevent skids by pumping the brakes.  The situation appears to be compounded by the dual-function brakes on the hybrid, which are designed to initially regenerate energy normally lost in braking and store it in the vehicle’s batteries.  Under more aggressive braking, or if the vehicle senses a skid, conventional hydraulic brakes take over.

The Prius/HS250h recall comes nearly a week after Toyota reversed course, initially denying the hybrids had braking problems and then, last week, saying it had already implemented a “fix,” in January, for vehicles rolling down its assembly lines.  A spokesman, Mike Michels, explained that the company had to confirm the repair, involving reprogramming software in the Prius brake controller, could be properly duplicated with vehicle already “in the field.”

The bigger question, some observers now ask is whether Toyota is looking at problems that could extend back prior to the 2010 model-year, something that a number of owners have been reporting to Toyota, the NHTSA – and to TheDetroitBureau.com, which has been hearing about brake-related issues dating back to as early as the 2005 model-year.

Among those are Jeff Zuhlke, of Wales, Wisconsin, who says he has experienced the feeling of brake loss, “many times,” under a number of conditions that would not be likely to disrupt the operation of other vehicles, “such as when I’ve gone over small depressions in the road while braking. I’ve also had that same sensation whenever I come to a stop at a specific stop light that has railroad tracks near the light.”

Another motorist who has reported problems is Susan Yonish, of Cornelius, North Carolina, a retiree who claims her vehicle “had an actual crash due to the brakes not stopping the car in bumper-to-bumper traffic.”

If, as Toyota noted, last week, the Prius’s brakes could release for as much as a second, that would be the equivalent of driving 44 feet, or roughly three car lengths, at just 30 miles an hour, a significant distance in heavy traffic.

“There seems to be braking issues going back” before the 2010 model-year, claims Sean Kane, a well-known, if controversial, figure in safety-related litigation circles.  He has been an outspoken critic of Toyota in regards to reports of so-called “unintended acceleration,” issues the maker is hoping to address through a pair of recent recalls, one to prevent carpet entrapment and the other to deal with sticky accelerators.

But like a number of critics, Kane, head of Safety Research and Strategies, Inc., in Rehoboth, Massachusetts, has questioned whether there are electronic gremlins at work, as well, particularly with the Prius, where reports of brake problems and of unintended acceleration, which he says, “may be related.”

Electronic glitches do seem to be showing up in the Prius, and in more than just the latest model, based on federal documents covering a range of issues, such as intermittent headlight failures.  How serious these problems are, and how they differ from other automakers’ electronic issues, remains to be seen. In the current atmosphere, many self-interested parties are piling on to a wounded Toyota, whose credibility has been severely damaged, and is now in the impossible position of trying to disprove a negative.

Toyota officials insist that the braking problem – which they initially downplayed – is limited to the 2010 model-year.  But it’s unclear why that would provide a sharp delineation.  Though the new model is billed as the third-generation hybrid, and has undergone some distinctive exterior and interior body updates, Toyota officials made a point of saying that there were no significant changes to the vehicle’s distinctive Hybrid Synergy Drive system, even though the displacement of the engine was bumped up to 1.8 liters.

Spokesman Michels says the key difference is not the drivetrain, but a recalibration to “reduce ABS over-sensitivity.”  Nonetheless, Toyota has previously acknowledged that there were some issues with earlier Prius traction control technology, which also involved the programming of the hybrid’s brake controller. (ABS, traction control, electronic stability control and various other technologies all rely, at least in part, on braking to improve the stopping, handling and stability of today’s cars, including Prius.)

And Toyota’s credibility has been stretched thin by recent events, including the ongoing pair of recalls, affecting more than 8 million vehicles, for unintended acceleration.  When the first recall was announced, last October, the automaker pointed its corporate finger at loose floor mats and decried talk of other possible problems as “unwarranted speculation.”  But on January 21, 2010, Toyota added millions of vehicles troubled by potentially sticky accelerators, covered under a second recall.  And while it continues to rule out electronic glitches, federal regulators are now making that possibility a high priority of their ramped-up investigation.

How far back problems with the Prius brakes do indeed go may not become clear until federal regulators and the automaker work through their extensive lists of owner complaints.  And the onging publicity involving the hybrid – the best-selling gas-electric model in the world and the single best-selling vehicle of any type in Japan – is generating a flood of new customer grievances.

But based on TheDetroitBureau.com’s research – which was triggered by owner concerns raised before the latest headlines – it appears there is a strong possibility that braking issues date back to at least the second-generation Prius, if not before.

TheDetroitBureau.com’s Editor-in-Chief Ken Zino and Contributing Editor Joe Szczesny contributed to this report.