Larry Jaques wrote:
....

Condensation (+ rust?) was apparently the culprit.
....

Don't know that we know...

Just got this from a embedded systems consulting guru whose newsletter I
subscribe to. His take at the moment--

Toyota Brakes
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Over the last few days I've received an avalanche of email from
engineers asking for my take on the "software problem" in certain
models of Toyotas that leads to runaway cars. The blogosphere is full
of speculation about the problem as well, so much that Toyota's
software seems to stand indicted, convicted and tried.

I drive a Toyota Prius, a hybrid that has a regenerative braking
system. I'm told the brake pedal is just an input to the computer
with no connection to the hydraulic system. After 102,000 miles it
has never failed to stop the car, but does feel very subtly "weird"
very occasionally, like there's just something different, something
unexpected in the feel of the braking system. But it has never felt
unsafe.

Engineers who design ABS brake systems tell me the software is
qualified by highly experienced test drivers who zoom around the
track and come back asking for a different "feel," which is something
that can't be embodied in formal requirements. It seems
software-controlled braking is designed to model the century-old
manual controls, to give the driver the experience he is used to.

My take on the current recall is: we know nothing. Software, floor
mats, mechanical problems - it could be one of these, all of them, or
something else entirely. When the NTSB sets off to investigate an
airplane crash they leave DC with the most important tool that an
investigator possesses: an open mind. As inquiring engineers it's fun
to speculate about potential root causes of accidents, but that's
simple speculation, nothing more.

I do predict that if the software is involved, the engineering
community will learn nothing useful from this experience. Surely
details of the bug will remain shrouded in secrecy. My hope is that
someday we open the books on bugs so, just as is true in civil
engineering and the aviation industry, others can learn from our
mistakes. Alas, for now that hope seems completely naive.

Excerpted from

About The Embedded Muse
-----------------------
The Embedded Muse is a newsletter sent via email by Jack Ganssle.
Send complaints, comments, and contributions to me at
.

The Embedded Muse is supported by The Ganssle Group, whose mission is
to help embedded folks get better products to market faster.
.... [snip] ...

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