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Re: [ST] Idle problem after refuelling and short journey



- ----- Original Message -----
From: "Brian Michaud"

> Neil,
>     Whoever told you this gibberish apparently the never traced the
> electrical path via the schematic in the service manual. The signal that
> travels from the ignition switch to the ECM goes through the kill switch
and
> the connector for the alarm before reaching the ECM.

After examining the schematic I have to agree --- somewhat.  From the
diagram it would appear that power to the ECM on pin 69 is removed
immediately by either turing off the ignition switch OR hitting the kill
switch.  That much I'll grant you.  But I don't think the ECM is actually
dead at this point because the ECM controls the Cooling Fan Relay (from ECM
pin 25) and we know there are times when the fan runs after the ignition
switch is turned off.  If I'm not mistaken, it looks to me like power is
also applied to pin 1 of the ECM by the ECM relay (shown as #72 on page
16.33) and it looks to me like that relay is energized by pin 86 of the ECM.
Obviously there's a lot more going on here than is apparent at first glance.

Whether the ECM actually reads sensors after the key is turned off was
actually moot to the original discussion.  The fault that was described as a
complete inability to idle has nothing to do with misuse of the kill switch
because I've seen the symptom and the kill switch was not being used at all
at the time.  As for your remarks about the ECM not needing to read sensors,
I'd be careful unless you purport to be an expert on Sagem fuel injection
systems.  I'm not, but I've heard it MANY times on this list before that it
is NOT a good idea to routinely use the kill switch on Triumph fuel-injected
bikes.  It may turn out that storing some of the sensor readings is more
beneficial if the bike is NOT allowed to cool down completely before the
re-start.  But I think that it is important for the ECM to know the position
of the crankshaft BEFORE the engine starts and I'm not sure if it can do
when the crank is not moving.  Likewise, it's probably good to know the
approximate barometric pressure, as well as air temperature for a good
start.

I'll bet Wayne MacDonald could shed a whole lot of light on ECM issues like
this.  After all he wrote the Tuneboy software, which is a clone of the the
Triumph 'gameboy' tool.   He seems to hang out more on the T5 list however.

Anyone else care to chime in on the kill switch issue?  -- I've squinted at
that diagram long enough -- and I've never had occasion to use the kill
switch cause I've not yet had that kind of emergency.  But if anyone can
decipher the electrical schematic better, or happens to know exactly what's
going on here, I'd be interested in hearing.

Neil




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