Page 107 - Toyota Under Fire

TOYOT A UNDER FIRE

Shielding the outside of the circuit is one method to pro-
tect against EMI, but we also do shielding in the device
itself using a . . . mesh type wire. You can also do that . . .
in the wires bundled into wire harnesses that run through
the vehicle to prevent these waves from traveling along
the wire and then getting into the [modules] through the
wire itself. There are ways to use grounding and capaci-
tors . . . to help [the system] shield itself. Keeping the
right distance between devices and using certain materi-
als to protect from the energy are other design consider-
ations. So, there’s more to consider in the design than just
the materials themselves. The circuit board design is prob-
ably the most critical: how you ground it, how many lay-
ers it has, how you lay out the components on the board.
All of those things are very standardized. There’s noth-
ing dramatically unique about Toyota in that respect.

Even with this fail-safe design, Toyota obsessively tests each
component, each subassembly, each complete system, and the en-
tire vehicle inside controlled test chambers and out in the world
in areas that are subject to high EMI. For more on how Toyota
tests electronic systems to ensure that they are safe from EMI, see
Toyota’s Electromagnetic Interference Testing, on pages 77 to 79.
Again, we emphasize that Toyota’s system for designing and
testing its electronics is incredibly sophisticated, but it is not
unique—all manufacturers, for obvious reasons, require their
electronic systems to meet rigorous design and testing standards.
This point is particularly important to understand because of the
history of complaints of unintended acceleration. Toyota is by no
means the first manufacturer to be accused of having a problem
with sudden unintended acceleration (SUA).

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