[V8] 2231 code hell update....

[dsaad at icehouse.net]

Yes - BUT...

the light bulb puts a more realistic load on the circuit. It also gives a
nice visual indication since the brightness is proportional to voltage -
so if the bulb flickers in relation to idle speed then there is a pretty
good chance the ECU is doing its job and the wires can support the current
load.  This helps to eliminate weak/corroded connections in the path.

A voltmeter across the bulb would be good too.  In fact, there is no need
at all for the light bulb if you have an analog meter - measure across the
ISV terminals.  Just watch the needle swing as idle speed changes.  Most
cheapo digital meters aren't very good at this kind of measurement though
because their reaction time is too slow.


An analogy: someone was working on a power window problem the other day. 
It would be possible to measure 12v on the supply wires at the door and
conclude that the circuit was good up to there - but measuring the same
wires when the switch is pressed may drop to close to zero volts - meaning
the circuit has a high resistance connection somewhere.  This is the usual
scenario that makes troubleshooting electrical problems so hard.


Dave

> Wouldn't a multimeter be the proper tool to use here?
>
>
>
> dsaad at icehouse.net wrote:
>
>>That may be a valid thing to do - I don't know how that circuit works but
>>keep in mind that you are driving un-fused battery voltage INTO an OUTPUT
>>of the ECU.  Generally speaking this is a bad thing to do.  It all
>> depends
>>on how the circuit works inside the ECU.
>>
>>I would do a safer test first - put a light bulb (small wattage like
>> maybe
>>a marker light bulb) at the connector for the ISV.  If it lights up, the
>>wires are good.  If you see it vary with engine speed then the ECU is
>>doing its job.  Exactly how bright the bulb should be is an unknown but
>>you could try this on two cars and compare results can't you?
>>
>>I can say that this is a two wire system. It works by varying the voltage
>>across the ISV coil which in turn causes an armature inside the ISV to
>>rotate in proportion to this voltage.  This should be easily visible with
>>the light bulb test.
>>
>>
>>Dave
>>
>>
>>> I'm still getting the code. 
>>> in addition I got the carbon canister code today and ISV code...which
>>> is
>>> different than the ISV control code I'm complaining about.
>>>
>>> So what Keith suggested to me is to unplug the ISV at the ISV and drive
>>> around. If the symptoms are still there then that would eliminate the
>>> ISV
>>> as being the problem. Next 
>>> I'm to run a jumper wire from the jump start post to the power wire at
>>> the
>>> ISV. If the problem goes away than there is a problem with the power
>>> wire.
>>> If it doesn't go away I'm to run a jumper wire from the back of the
>>> fuse
>>> at the fuse block for the ISV to the power wire for the ISV at the
>>> coastal
>>> connector.
>>> Â All the above will eliminate whats wrong and whats not.This sound
>>> about
>>> rite?
>>> Â Ron
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>>
>>
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