> <sycore@bellsouth.net> wrote in message
> news:Rz2Kf.11195$UD1.10844@bignews2.bellsouth.net. ..
>> Hi,
>>
>> I have a 2003 tiburon that is getting no spark. The sensor fuse in the
>> engine compartment fuse box keeps blowing immediatly when i try to start,
>> so
>> i suspect
>> that it is causing the no spark condition. Using hyundai's interactive
>> schematic index i see the engine compartment sensor fuse controls the
>> Canister close valve directly and also the canister purge, MAF, TPS, Cam
>> and
>> Crank position sensor as well as the idle speed control. I am assuming
>> one
>> has a short or has gone bad.
>> I will be getting a code scanner in a few days so hopefully it will
>> indicate
>> which one has the problem. My question is has anyone had one of these
>> fail
>> causing a no spark condition. I am leaning towards the canster close
>> valve
>> or purge, because i think the others would let it start, but it would
>> just
>> run bad. Any help is apprecaited.
>>
>> Thanks in advance
>> kirk2@bollywoodmail.com
>>
>
A scan tool won't help. You've already located the problem - an apparent
short on the power source for several critical devices. The cam and crank
position sensors are what tells the ecm when to fire which coil. You need
to
find what's blowing the fuse. The likely place to start is to find C42 /
C142 (you don't say which engine), and open up the pins leaving it, and
look
at which device has the short on it's power supply lead. Use a meter, don't
keep putting fuses in it. You might also look at the resistance to ground
on
the downstream side of the fuse. Start disconnecting things like the TPS,
O2
sensors, etc., and see what makes the short go away.

 

it is the 2.7L v6 engine.
I have a multimeter and can do the basics, but i am not the advanced in
testing.
The fuse pops about 3-4 seconds after i turn the ignition key to on
position.
I can easily unplug all of the sesors except maybe the canister close valve.
Can i just plug them back in one at a time until it pops?

"Bob" <bobsjunkmail@bellsouth.net> wrote in message
news:MxaKf.48729$697.47623@bignews3.bellsouth.net. ..
> > <sycore@bellsouth.net> wrote in message
> > news:Rz2Kf.11195$UD1.10844@bignews2.bellsouth.net. ..
> >> Hi,
> >>
> >> I have a 2003 tiburon that is getting no spark. The sensor fuse in the
> >> engine compartment fuse box keeps blowing immediatly when i try to
start,
> >> so
> >> i suspect
> >> that it is causing the no spark condition. Using hyundai's interactive
> >> schematic index i see the engine compartment sensor fuse controls the
> >> Canister close valve directly and also the canister purge, MAF, TPS,
Cam
> >> and
> >> Crank position sensor as well as the idle speed control. I am assuming
> >> one
> >> has a short or has gone bad.
> >> I will be getting a code scanner in a few days so hopefully it will
> >> indicate
> >> which one has the problem. My question is has anyone had one of these
> >> fail
> >> causing a no spark condition. I am leaning towards the canster close
> >> valve
> >> or purge, because i think the others would let it start, but it would
> >> just
> >> run bad. Any help is apprecaited.
> >>
> >> Thanks in advance
> >> kirk2@bollywoodmail.com
> >>
> >
> A scan tool won't help. You've already located the problem - an apparent
> short on the power source for several critical devices. The cam and crank
> position sensors are what tells the ecm when to fire which coil. You need
> to
> find what's blowing the fuse. The likely place to start is to find C42 /
> C142 (you don't say which engine), and open up the pins leaving it, and
> look
> at which device has the short on it's power supply lead. Use a meter,
don't
> keep putting fuses in it. You might also look at the resistance to ground
> on
> the downstream side of the fuse. Start disconnecting things like the TPS,
> O2
> sensors, etc., and see what makes the short go away.
>
>

 

it is the 2.7L v6 engine.
I have a multimeter and can do the basics, but i am not the advanced in
testing.
The fuse pops about 3-4 seconds after i turn the ignition key to on
position.
I can easily unplug all of the sesors except maybe the canister close valve.
Can i just plug them back in one at a time until it pops?

"Bob" <bobsjunkmail@bellsouth.net> wrote in message
news:MxaKf.48729$697.47623@bignews3.bellsouth.net. ..
> > <sycore@bellsouth.net> wrote in message
> > news:Rz2Kf.11195$UD1.10844@bignews2.bellsouth.net. ..
> >> Hi,
> >>
> >> I have a 2003 tiburon that is getting no spark. The sensor fuse in the
> >> engine compartment fuse box keeps blowing immediatly when i try to
start,
> >> so
> >> i suspect
> >> that it is causing the no spark condition. Using hyundai's interactive
> >> schematic index i see the engine compartment sensor fuse controls the
> >> Canister close valve directly and also the canister purge, MAF, TPS,
Cam
> >> and
> >> Crank position sensor as well as the idle speed control. I am assuming
> >> one
> >> has a short or has gone bad.
> >> I will be getting a code scanner in a few days so hopefully it will
> >> indicate
> >> which one has the problem. My question is has anyone had one of these
> >> fail
> >> causing a no spark condition. I am leaning towards the canster close
> >> valve
> >> or purge, because i think the others would let it start, but it would
> >> just
> >> run bad. Any help is apprecaited.
> >>
> >> Thanks in advance
> >> kirk2@bollywoodmail.com
> >>
> >
> A scan tool won't help. You've already located the problem - an apparent
> short on the power source for several critical devices. The cam and crank
> position sensors are what tells the ecm when to fire which coil. You need
> to
> find what's blowing the fuse. The likely place to start is to find C42 /
> C142 (you don't say which engine), and open up the pins leaving it, and
> look
> at which device has the short on it's power supply lead. Use a meter,
don't
> keep putting fuses in it. You might also look at the resistance to ground
> on
> the downstream side of the fuse. Start disconnecting things like the TPS,
> O2
> sensors, etc., and see what makes the short go away.
>
>

 

it is the 2.7L v6 engine.
I have a multimeter and can do the basics, but i am not the advanced in
testing.
The fuse pops about 3-4 seconds after i turn the ignition key to on
position.
I can easily unplug all of the sesors except maybe the canister close valve.
Can i just plug them back in one at a time until it pops?

"Bob" <bobsjunkmail@bellsouth.net> wrote in message
news:MxaKf.48729$697.47623@bignews3.bellsouth.net. ..
> > <sycore@bellsouth.net> wrote in message
> > news:Rz2Kf.11195$UD1.10844@bignews2.bellsouth.net. ..
> >> Hi,
> >>
> >> I have a 2003 tiburon that is getting no spark. The sensor fuse in the
> >> engine compartment fuse box keeps blowing immediatly when i try to
start,
> >> so
> >> i suspect
> >> that it is causing the no spark condition. Using hyundai's interactive
> >> schematic index i see the engine compartment sensor fuse controls the
> >> Canister close valve directly and also the canister purge, MAF, TPS,
Cam
> >> and
> >> Crank position sensor as well as the idle speed control. I am assuming
> >> one
> >> has a short or has gone bad.
> >> I will be getting a code scanner in a few days so hopefully it will
> >> indicate
> >> which one has the problem. My question is has anyone had one of these
> >> fail
> >> causing a no spark condition. I am leaning towards the canster close
> >> valve
> >> or purge, because i think the others would let it start, but it would
> >> just
> >> run bad. Any help is apprecaited.
> >>
> >> Thanks in advance
> >> kirk2@bollywoodmail.com
> >>
> >
> A scan tool won't help. You've already located the problem - an apparent
> short on the power source for several critical devices. The cam and crank
> position sensors are what tells the ecm when to fire which coil. You need
> to
> find what's blowing the fuse. The likely place to start is to find C42 /
> C142 (you don't say which engine), and open up the pins leaving it, and
> look
> at which device has the short on it's power supply lead. Use a meter,
don't
> keep putting fuses in it. You might also look at the resistance to ground
> on
> the downstream side of the fuse. Start disconnecting things like the TPS,
> O2
> sensors, etc., and see what makes the short go away.
>
>

 

<sycore@bellsouth.net> wrote in message
news:kSbKf.20004$bW.11031@bignews8.bellsouth.net.. .
> it is the 2.7L v6 engine.
> I have a multimeter and can do the basics, but i am not the advanced in
> testing.
> The fuse pops about 3-4 seconds after i turn the ignition key to on
> position.
> I can easily unplug all of the sesors except maybe the canister close
> valve.
> Can i just plug them back in one at a time until it pops?

3-4 seconds means no "hard" short. You can try that, but without quite a bit
of electrical troubleshooting experience, you can get in over your head
pretty quickly.

 

<sycore@bellsouth.net> wrote in message
news:kSbKf.20004$bW.11031@bignews8.bellsouth.net.. .
> it is the 2.7L v6 engine.
> I have a multimeter and can do the basics, but i am not the advanced in
> testing.
> The fuse pops about 3-4 seconds after i turn the ignition key to on
> position.
> I can easily unplug all of the sesors except maybe the canister close
> valve.
> Can i just plug them back in one at a time until it pops?

3-4 seconds means no "hard" short. You can try that, but without quite a bit
of electrical troubleshooting experience, you can get in over your head
pretty quickly.

 

<sycore@bellsouth.net> wrote in message
news:kSbKf.20004$bW.11031@bignews8.bellsouth.net.. .
> it is the 2.7L v6 engine.
> I have a multimeter and can do the basics, but i am not the advanced in
> testing.
> The fuse pops about 3-4 seconds after i turn the ignition key to on
> position.
> I can easily unplug all of the sesors except maybe the canister close
> valve.
> Can i just plug them back in one at a time until it pops?

3-4 seconds means no "hard" short. You can try that, but without quite a bit
of electrical troubleshooting experience, you can get in over your head
pretty quickly.

 

"Bob" <bobsjunkmail@bellsouth.net> wrote in message
news:jaiKf.20641$bW.19251@bignews8.bellsouth.net.. .
>
> <sycore@bellsouth.net> wrote in message
> news:kSbKf.20004$bW.11031@bignews8.bellsouth.net.. .
> > it is the 2.7L v6 engine.
> > I have a multimeter and can do the basics, but i am not the advanced in
> > testing.
> > The fuse pops about 3-4 seconds after i turn the ignition key to on
> > position.
> > I can easily unplug all of the sesors except maybe the canister close
> > valve.
> > Can i just plug them back in one at a time until it pops?
>
> 3-4 seconds means no "hard" short. You can try that, but without quite a
bit
> of electrical troubleshooting experience, you can get in over your head
> pretty quickly.
>
>

I don't know what the schematics show for this circuit Bob, but he'd likely
be ok at least trying this approach - assuming that the circuit does really
consist of the components the OP first indicated.

You're right that 3-4 seconds implies a short with a resistance and not a
direct short., and that kind of troubleshooting with a meter can get
confusing for folks who are not a little experienced. Depending upon how
the meter is set, it can potentially either look like a direct short
(leading to replacing the wrong component in vain), or not even show the
short (leading to the obvious oversight).

I think in this case - again, assuming the circuit is as described, just go
ahead as the OP suggests and disconnect the loads and selectively re-connect
them. The caution with this technique is to make sure to inspect the wiring
as well as the components.

Over his head pretty quickly??? Hell - every time I get into
troubleshooting automobile wiring/electronics I make the same statement - "I
hate working on car wiring". But... I do it, and I've been doing it a long
time, so I understand this stuff pretty well, but I still hate it!

--

-Mike-
mmarlowREMOVE@alltel.net

 

"Bob" <bobsjunkmail@bellsouth.net> wrote in message
news:jaiKf.20641$bW.19251@bignews8.bellsouth.net.. .
>
> <sycore@bellsouth.net> wrote in message
> news:kSbKf.20004$bW.11031@bignews8.bellsouth.net.. .
> > it is the 2.7L v6 engine.
> > I have a multimeter and can do the basics, but i am not the advanced in
> > testing.
> > The fuse pops about 3-4 seconds after i turn the ignition key to on
> > position.
> > I can easily unplug all of the sesors except maybe the canister close
> > valve.
> > Can i just plug them back in one at a time until it pops?
>
> 3-4 seconds means no "hard" short. You can try that, but without quite a
bit
> of electrical troubleshooting experience, you can get in over your head
> pretty quickly.
>
>

I don't know what the schematics show for this circuit Bob, but he'd likely
be ok at least trying this approach - assuming that the circuit does really
consist of the components the OP first indicated.

You're right that 3-4 seconds implies a short with a resistance and not a
direct short., and that kind of troubleshooting with a meter can get
confusing for folks who are not a little experienced. Depending upon how
the meter is set, it can potentially either look like a direct short
(leading to replacing the wrong component in vain), or not even show the
short (leading to the obvious oversight).

I think in this case - again, assuming the circuit is as described, just go
ahead as the OP suggests and disconnect the loads and selectively re-connect
them. The caution with this technique is to make sure to inspect the wiring
as well as the components.

Over his head pretty quickly??? Hell - every time I get into
troubleshooting automobile wiring/electronics I make the same statement - "I
hate working on car wiring". But... I do it, and I've been doing it a long
time, so I understand this stuff pretty well, but I still hate it!

--

-Mike-
mmarlowREMOVE@alltel.net

 

"Bob" <bobsjunkmail@bellsouth.net> wrote in message
news:jaiKf.20641$bW.19251@bignews8.bellsouth.net.. .
>
> <sycore@bellsouth.net> wrote in message
> news:kSbKf.20004$bW.11031@bignews8.bellsouth.net.. .
> > it is the 2.7L v6 engine.
> > I have a multimeter and can do the basics, but i am not the advanced in
> > testing.
> > The fuse pops about 3-4 seconds after i turn the ignition key to on
> > position.
> > I can easily unplug all of the sesors except maybe the canister close
> > valve.
> > Can i just plug them back in one at a time until it pops?
>
> 3-4 seconds means no "hard" short. You can try that, but without quite a
bit
> of electrical troubleshooting experience, you can get in over your head
> pretty quickly.
>
>

I don't know what the schematics show for this circuit Bob, but he'd likely
be ok at least trying this approach - assuming that the circuit does really
consist of the components the OP first indicated.

You're right that 3-4 seconds implies a short with a resistance and not a
direct short., and that kind of troubleshooting with a meter can get
confusing for folks who are not a little experienced. Depending upon how
the meter is set, it can potentially either look like a direct short
(leading to replacing the wrong component in vain), or not even show the
short (leading to the obvious oversight).

I think in this case - again, assuming the circuit is as described, just go
ahead as the OP suggests and disconnect the loads and selectively re-connect
them. The caution with this technique is to make sure to inspect the wiring
as well as the components.

Over his head pretty quickly??? Hell - every time I get into
troubleshooting automobile wiring/electronics I make the same statement - "I
hate working on car wiring". But... I do it, and I've been doing it a long
time, so I understand this stuff pretty well, but I still hate it!

--

-Mike-
mmarlowREMOVE@alltel.net

 

"Mike Marlow" <mmarlowREMOVE@alltel.net> wrote in message
news:dea96$43f9b46f$4528960b$13829@ALLTEL.NET...
>
> "Bob" <bobsjunkmail@bellsouth.net> wrote in message
> news:jaiKf.20641$bW.19251@bignews8.bellsouth.net.. .
>>
>> <sycore@bellsouth.net> wrote in message
>> news:kSbKf.20004$bW.11031@bignews8.bellsouth.net.. .
>> > it is the 2.7L v6 engine.
>> > I have a multimeter and can do the basics, but i am not the advanced in
>> > testing.
>> > The fuse pops about 3-4 seconds after i turn the ignition key to on
>> > position.
>> > I can easily unplug all of the sesors except maybe the canister close
>> > valve.
>> > Can i just plug them back in one at a time until it pops?
>>
>> 3-4 seconds means no "hard" short. You can try that, but without quite a
> bit
>> of electrical troubleshooting experience, you can get in over your head
>> pretty quickly.
>>
>>
>
> I don't know what the schematics show for this circuit Bob, but he'd
> likely
> be ok at least trying this approach - assuming that the circuit does
> really
> consist of the components the OP first indicated.
>
> You're right that 3-4 seconds implies a short with a resistance and not a
> direct short., and that kind of troubleshooting with a meter can get
> confusing for folks who are not a little experienced. Depending upon how
> the meter is set, it can potentially either look like a direct short
> (leading to replacing the wrong component in vain), or not even show the
> short (leading to the obvious oversight).
>
> I think in this case - again, assuming the circuit is as described, just
> go
> ahead as the OP suggests and disconnect the loads and selectively
> re-connect
> them. The caution with this technique is to make sure to inspect the
> wiring
> as well as the components.
>
> Over his head pretty quickly??? Hell - every time I get into
> troubleshooting automobile wiring/electronics I make the same statement -
> "I
> hate working on car wiring". But... I do it, and I've been doing it a
> long
> time, so I understand this stuff pretty well, but I still hate it!
>
> --
>
> -Mike-
> mmarlowREMOVE@alltel.net
>
What concerns me is given that there's a delay before the fuse blows, and
wiring at 12 volts typically can't fail in a way that gives a high
resistance short that's hard enough that it blows a fuse. If it were a high
resistance short, he'd be dissipating about 240 watts (~12 volts at ~20 amps
to blow a 10 amp fuse in a short but not instant time) at that high
resistance point - much smoke would be present. The other possibility is a
motion induced hard short to ground. If he in fact has something that is
driven - a valve, etc - that has a short, and there's a delay before that
device is actuated, he runs the possibility of damaging the driver. I mean,
how many times can an output take a short before failing. To try to explain
to use a current limiting device in place of a fuse for troubleshooting - a
lamp, etc.- and what the results should be is really difficult.

 

"Mike Marlow" <mmarlowREMOVE@alltel.net> wrote in message
news:dea96$43f9b46f$4528960b$13829@ALLTEL.NET...
>
> "Bob" <bobsjunkmail@bellsouth.net> wrote in message
> news:jaiKf.20641$bW.19251@bignews8.bellsouth.net.. .
>>
>> <sycore@bellsouth.net> wrote in message
>> news:kSbKf.20004$bW.11031@bignews8.bellsouth.net.. .
>> > it is the 2.7L v6 engine.
>> > I have a multimeter and can do the basics, but i am not the advanced in
>> > testing.
>> > The fuse pops about 3-4 seconds after i turn the ignition key to on
>> > position.
>> > I can easily unplug all of the sesors except maybe the canister close
>> > valve.
>> > Can i just plug them back in one at a time until it pops?
>>
>> 3-4 seconds means no "hard" short. You can try that, but without quite a
> bit
>> of electrical troubleshooting experience, you can get in over your head
>> pretty quickly.
>>
>>
>
> I don't know what the schematics show for this circuit Bob, but he'd
> likely
> be ok at least trying this approach - assuming that the circuit does
> really
> consist of the components the OP first indicated.
>
> You're right that 3-4 seconds implies a short with a resistance and not a
> direct short., and that kind of troubleshooting with a meter can get
> confusing for folks who are not a little experienced. Depending upon how
> the meter is set, it can potentially either look like a direct short
> (leading to replacing the wrong component in vain), or not even show the
> short (leading to the obvious oversight).
>
> I think in this case - again, assuming the circuit is as described, just
> go
> ahead as the OP suggests and disconnect the loads and selectively
> re-connect
> them. The caution with this technique is to make sure to inspect the
> wiring
> as well as the components.
>
> Over his head pretty quickly??? Hell - every time I get into
> troubleshooting automobile wiring/electronics I make the same statement -
> "I
> hate working on car wiring". But... I do it, and I've been doing it a
> long
> time, so I understand this stuff pretty well, but I still hate it!
>
> --
>
> -Mike-
> mmarlowREMOVE@alltel.net
>
What concerns me is given that there's a delay before the fuse blows, and
wiring at 12 volts typically can't fail in a way that gives a high
resistance short that's hard enough that it blows a fuse. If it were a high
resistance short, he'd be dissipating about 240 watts (~12 volts at ~20 amps
to blow a 10 amp fuse in a short but not instant time) at that high
resistance point - much smoke would be present. The other possibility is a
motion induced hard short to ground. If he in fact has something that is
driven - a valve, etc - that has a short, and there's a delay before that
device is actuated, he runs the possibility of damaging the driver. I mean,
how many times can an output take a short before failing. To try to explain
to use a current limiting device in place of a fuse for troubleshooting - a
lamp, etc.- and what the results should be is really difficult.

 

"Mike Marlow" <mmarlowREMOVE@alltel.net> wrote in message
news:dea96$43f9b46f$4528960b$13829@ALLTEL.NET...
>
> "Bob" <bobsjunkmail@bellsouth.net> wrote in message
> news:jaiKf.20641$bW.19251@bignews8.bellsouth.net.. .
>>
>> <sycore@bellsouth.net> wrote in message
>> news:kSbKf.20004$bW.11031@bignews8.bellsouth.net.. .
>> > it is the 2.7L v6 engine.
>> > I have a multimeter and can do the basics, but i am not the advanced in
>> > testing.
>> > The fuse pops about 3-4 seconds after i turn the ignition key to on
>> > position.
>> > I can easily unplug all of the sesors except maybe the canister close
>> > valve.
>> > Can i just plug them back in one at a time until it pops?
>>
>> 3-4 seconds means no "hard" short. You can try that, but without quite a
> bit
>> of electrical troubleshooting experience, you can get in over your head
>> pretty quickly.
>>
>>
>
> I don't know what the schematics show for this circuit Bob, but he'd
> likely
> be ok at least trying this approach - assuming that the circuit does
> really
> consist of the components the OP first indicated.
>
> You're right that 3-4 seconds implies a short with a resistance and not a
> direct short., and that kind of troubleshooting with a meter can get
> confusing for folks who are not a little experienced. Depending upon how
> the meter is set, it can potentially either look like a direct short
> (leading to replacing the wrong component in vain), or not even show the
> short (leading to the obvious oversight).
>
> I think in this case - again, assuming the circuit is as described, just
> go
> ahead as the OP suggests and disconnect the loads and selectively
> re-connect
> them. The caution with this technique is to make sure to inspect the
> wiring
> as well as the components.
>
> Over his head pretty quickly??? Hell - every time I get into
> troubleshooting automobile wiring/electronics I make the same statement -
> "I
> hate working on car wiring". But... I do it, and I've been doing it a
> long
> time, so I understand this stuff pretty well, but I still hate it!
>
> --
>
> -Mike-
> mmarlowREMOVE@alltel.net
>
What concerns me is given that there's a delay before the fuse blows, and
wiring at 12 volts typically can't fail in a way that gives a high
resistance short that's hard enough that it blows a fuse. If it were a high
resistance short, he'd be dissipating about 240 watts (~12 volts at ~20 amps
to blow a 10 amp fuse in a short but not instant time) at that high
resistance point - much smoke would be present. The other possibility is a
motion induced hard short to ground. If he in fact has something that is
driven - a valve, etc - that has a short, and there's a delay before that
device is actuated, he runs the possibility of damaging the driver. I mean,
how many times can an output take a short before failing. To try to explain
to use a current limiting device in place of a fuse for troubleshooting - a
lamp, etc.- and what the results should be is really difficult.

 

On Mon, 20 Feb 2006 18:13:22 -0500, "Bob" <bobsjunkmail@bellsouth.net>
wrote:

>
>"Mike Marlow" <mmarlowREMOVE@alltel.net> wrote in message
>news:dea96$43f9b46f$4528960b$13829@ALLTEL.NET.. .
>>
>> "Bob" <bobsjunkmail@bellsouth.net> wrote in message
>> news:jaiKf.20641$bW.19251@bignews8.bellsouth.net.. .
>>>
>>> <sycore@bellsouth.net> wrote in message
>>> news:kSbKf.20004$bW.11031@bignews8.bellsouth.net.. .
>>> > it is the 2.7L v6 engine.
>>> > I have a multimeter and can do the basics, but i am not the advanced in
>>> > testing.
>>> > The fuse pops about 3-4 seconds after i turn the ignition key to on
>>> > position.
>>> > I can easily unplug all of the sesors except maybe the canister close
>>> > valve.
>>> > Can i just plug them back in one at a time until it pops?
>>>
>>> 3-4 seconds means no "hard" short. You can try that, but without quite a
>> bit
>>> of electrical troubleshooting experience, you can get in over your head
>>> pretty quickly.
>>>
>>>
>>
>> I don't know what the schematics show for this circuit Bob, but he'd
>> likely
>> be ok at least trying this approach - assuming that the circuit does
>> really
>> consist of the components the OP first indicated.
>>
>> You're right that 3-4 seconds implies a short with a resistance and not a
>> direct short., and that kind of troubleshooting with a meter can get
>> confusing for folks who are not a little experienced. Depending upon how
>> the meter is set, it can potentially either look like a direct short
>> (leading to replacing the wrong component in vain), or not even show the
>> short (leading to the obvious oversight).
>>
>> I think in this case - again, assuming the circuit is as described, just
>> go
>> ahead as the OP suggests and disconnect the loads and selectively
>> re-connect
>> them. The caution with this technique is to make sure to inspect the
>> wiring
>> as well as the components.
>>
>> Over his head pretty quickly??? Hell - every time I get into
>> troubleshooting automobile wiring/electronics I make the same statement -
>> "I
>> hate working on car wiring". But... I do it, and I've been doing it a
>> long
>> time, so I understand this stuff pretty well, but I still hate it!
>>
>> --
>>
>> -Mike-
>> mmarlowREMOVE@alltel.net
>>
>What concerns me is given that there's a delay before the fuse blows, and
>wiring at 12 volts typically can't fail in a way that gives a high
>resistance short that's hard enough that it blows a fuse. If it were a high
>resistance short, he'd be dissipating about 240 watts (~12 volts at ~20 amps
>to blow a 10 amp fuse in a short but not instant time) at that high
>resistance point - much smoke would be present. The other possibility is a
>motion induced hard short to ground. If he in fact has something that is
>driven - a valve, etc - that has a short, and there's a delay before that
>device is actuated, he runs the possibility of damaging the driver. I mean,
>how many times can an output take a short before failing. To try to explain
>to use a current limiting device in place of a fuse for troubleshooting - a
>lamp, etc.- and what the results should be is really difficult.
>

I disagree. If it's a 10A circuit the normal load would be
~12/10=1.2 ohm. It's going to look like a short to anything but a
specialty resistance measuring circuit. I doubt it's really that low
and it is not that low per sensor so measuring may locate the bad
sensor. I would expect something like a 50% safety factor on the fuse
so I'd expect an agregate load of ~2.4 ohms. Each individual load
will be over that. Possibly well over that. If the circuit wiring is
properly sized it will not smoke with that load. I have seen
connectors with an ohm or more in a bad connection.

Polarity probably will also be an issue. You are going to need to use
the positive voltage resistance lead on the power lead to the sensor.
If you are not sure what one that is use a second meter set to measure
voltage and measure the voltage accross the probes of your resistance
meter.

Once You know the polarity probe the leads to the sensors with any
ground lead connected to the chassis. I bet several will be over 100
ohms so you can discount them for a first pass. If one is clearly
below 2 or 3 ohms it is probably the problem. If all of them look OK
then it is probably a function of the sensor activating and drawing
too much current. The easiest way to find that will be to disconnect
all of them then reconnect one at a time. You can either wait for the
fuse to blow or connect an ammeter accross a blown fuse. Monitor the
current draw as each sensor is connected. If I was doing this much
that is what I would start with. ;-)

If the fuse is blowing with the key on but not cranking the engine I
bet you will find the answer fairly easily. You probaly have a blown
semiconductor junction. It still has resistance, as does the
packaging leads, but it's well below what it should be.

nothermark

 

On Mon, 20 Feb 2006 18:13:22 -0500, "Bob" <bobsjunkmail@bellsouth.net>
wrote:

>
>"Mike Marlow" <mmarlowREMOVE@alltel.net> wrote in message
>news:dea96$43f9b46f$4528960b$13829@ALLTEL.NET.. .
>>
>> "Bob" <bobsjunkmail@bellsouth.net> wrote in message
>> news:jaiKf.20641$bW.19251@bignews8.bellsouth.net.. .
>>>
>>> <sycore@bellsouth.net> wrote in message
>>> news:kSbKf.20004$bW.11031@bignews8.bellsouth.net.. .
>>> > it is the 2.7L v6 engine.
>>> > I have a multimeter and can do the basics, but i am not the advanced in
>>> > testing.
>>> > The fuse pops about 3-4 seconds after i turn the ignition key to on
>>> > position.
>>> > I can easily unplug all of the sesors except maybe the canister close
>>> > valve.
>>> > Can i just plug them back in one at a time until it pops?
>>>
>>> 3-4 seconds means no "hard" short. You can try that, but without quite a
>> bit
>>> of electrical troubleshooting experience, you can get in over your head
>>> pretty quickly.
>>>
>>>
>>
>> I don't know what the schematics show for this circuit Bob, but he'd
>> likely
>> be ok at least trying this approach - assuming that the circuit does
>> really
>> consist of the components the OP first indicated.
>>
>> You're right that 3-4 seconds implies a short with a resistance and not a
>> direct short., and that kind of troubleshooting with a meter can get
>> confusing for folks who are not a little experienced. Depending upon how
>> the meter is set, it can potentially either look like a direct short
>> (leading to replacing the wrong component in vain), or not even show the
>> short (leading to the obvious oversight).
>>
>> I think in this case - again, assuming the circuit is as described, just
>> go
>> ahead as the OP suggests and disconnect the loads and selectively
>> re-connect
>> them. The caution with this technique is to make sure to inspect the
>> wiring
>> as well as the components.
>>
>> Over his head pretty quickly??? Hell - every time I get into
>> troubleshooting automobile wiring/electronics I make the same statement -
>> "I
>> hate working on car wiring". But... I do it, and I've been doing it a
>> long
>> time, so I understand this stuff pretty well, but I still hate it!
>>
>> --
>>
>> -Mike-
>> mmarlowREMOVE@alltel.net
>>
>What concerns me is given that there's a delay before the fuse blows, and
>wiring at 12 volts typically can't fail in a way that gives a high
>resistance short that's hard enough that it blows a fuse. If it were a high
>resistance short, he'd be dissipating about 240 watts (~12 volts at ~20 amps
>to blow a 10 amp fuse in a short but not instant time) at that high
>resistance point - much smoke would be present. The other possibility is a
>motion induced hard short to ground. If he in fact has something that is
>driven - a valve, etc - that has a short, and there's a delay before that
>device is actuated, he runs the possibility of damaging the driver. I mean,
>how many times can an output take a short before failing. To try to explain
>to use a current limiting device in place of a fuse for troubleshooting - a
>lamp, etc.- and what the results should be is really difficult.
>

I disagree. If it's a 10A circuit the normal load would be
~12/10=1.2 ohm. It's going to look like a short to anything but a
specialty resistance measuring circuit. I doubt it's really that low
and it is not that low per sensor so measuring may locate the bad
sensor. I would expect something like a 50% safety factor on the fuse
so I'd expect an agregate load of ~2.4 ohms. Each individual load
will be over that. Possibly well over that. If the circuit wiring is
properly sized it will not smoke with that load. I have seen
connectors with an ohm or more in a bad connection.

Polarity probably will also be an issue. You are going to need to use
the positive voltage resistance lead on the power lead to the sensor.
If you are not sure what one that is use a second meter set to measure
voltage and measure the voltage accross the probes of your resistance
meter.

Once You know the polarity probe the leads to the sensors with any
ground lead connected to the chassis. I bet several will be over 100
ohms so you can discount them for a first pass. If one is clearly
below 2 or 3 ohms it is probably the problem. If all of them look OK
then it is probably a function of the sensor activating and drawing
too much current. The easiest way to find that will be to disconnect
all of them then reconnect one at a time. You can either wait for the
fuse to blow or connect an ammeter accross a blown fuse. Monitor the
current draw as each sensor is connected. If I was doing this much
that is what I would start with. ;-)

If the fuse is blowing with the key on but not cranking the engine I
bet you will find the answer fairly easily. You probaly have a blown
semiconductor junction. It still has resistance, as does the
packaging leads, but it's well below what it should be.

nothermark