Not deliberately, but effectively yes. As I said it was a wiring design
error that they didn't notice, because the anti-runon system was just as
effective at stopping the engine as the ignition! It's only when people
have a problem with the emissions plumbing, or the anti-runon components,
that they then discover they can't switch off the engine with the key, which
is a not uncommon complaint in the past. UK cars never had the emissions
plumbing so the problem was discovered immediately, and corrected, but they
never applied the fix to North American cars.
What happens is that the ignition relay controls everything, except the
ignition warning light, which is still connected to the ignition switch as
before, and crucially to the same point as the relay winding. With the
ignition on and the engine running there is 12v to one side of the warning
light from the ignition key, and 12v to the other side from the alternator,
which is why the warning light doesn't glow. When the ignition is turned
off with a running engine, 12v is removed from the key side, but the
alternator is still generating 12v. Because the ignition switch side of the
warning light is also connected to the ignition relay winding, current flows
from the alternator, through the warning light and the relay winding, and
this is sufficient to keep the relay operated, hence all the ignition
circuits, including the coil, are still powered with the key off. Turning
off the key also operates the anti-runon system, which is so effective it
stops the engine as if the ignition *had* been turned off, hence no one
realised there was a problem.
PaulH.
----- Original Message -----
> Paul, Are you saying they cut the engine with the anti runon valve and
> actually delayed cutting power or are you simplifying? I'm looking at
> the
> later N American wiring diagram and I don't see any way they are delaying
> ignition cut off...
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