No charge, no speedo

"Spdloader" > wrote in message
. ..
> Hi, I'm new to the group, but my daughter has a Honda now so I'll be
> lurking.
> I didn't find anything on this exact problem in a search so:
>
> Vehicle is a 1998 Civic DX 5spd.
>
> Dead battery prompted a test of the alternator, which wasn't charging at
> all.
> Replaced alternator, and externally charged battery overnight. The car
> started fine the next morning, and it worked fine for about 1/2 a day,
> charging between 13.8v and 14.2v, then the speedo quit working, then that
> evening the headlights were dim.
>
> Next morning, battery was weak again, I charged the battery for a while,
> then started it, but now there is a no charge condition again, verified
> with a Fluke meter at the battery, but not at the alternator.
>
> A brief check of the fuse block under the dash revealed a blown 10A fuse,
> Alternator / Speedo. Replaced it, had a charge at the battery, then blew
> the fuse when moving the vehicle in the driveway.
>
> I suspect the vehicle speed sensor has a bad connection or is
> malfunctioning. Any other ideas before I dive back in tomorrow?
>
> Thanks in advance!
>
> Spdloader
>

Alternator taken off and tested, charged 20volts, 20amps on the bench, and
voltage regulator bad.

New alternator installed, worked perfectly for 5 mins, then fuse blew, and
I'm right back to square one.

Gonna go have a Mt. Dew now.

Spdloader

Spdloader wrote:
> "Spdloader" > wrote in message
> . ..
>
>>Hi, I'm new to the group, but my daughter has a Honda now so I'll be
>>lurking.
>>I didn't find anything on this exact problem in a search so:
>>
>>Vehicle is a 1998 Civic DX 5spd.
>>
>>Dead battery prompted a test of the alternator, which wasn't charging at
>>all.
>>Replaced alternator, and externally charged battery overnight. The car
>>started fine the next morning, and it worked fine for about 1/2 a day,
>>charging between 13.8v and 14.2v, then the speedo quit working, then that
>>evening the headlights were dim.
>>
>>Next morning, battery was weak again, I charged the battery for a while,
>>then started it, but now there is a no charge condition again, verified
>>with a Fluke meter at the battery, but not at the alternator.
>>
>>A brief check of the fuse block under the dash revealed a blown 10A fuse,
>>Alternator / Speedo. Replaced it, had a charge at the battery, then blew
>>the fuse when moving the vehicle in the driveway.
>>
>>I suspect the vehicle speed sensor has a bad connection or is
>>malfunctioning. Any other ideas before I dive back in tomorrow?
>>
>>Thanks in advance!
>>
>>Spdloader
>>
>
>
> Alternator taken off and tested, charged 20volts, 20amps on the bench, and
> voltage regulator bad.
>
> New alternator installed, worked perfectly for 5 mins, then fuse blew, and
> I'm right back to square one.
>
> Gonna go have a Mt. Dew now.

So something else is killing the voltage regulator(s - 4 of them now!),
which then of course isn't regulating the output properly. Going by the
schematic I found for the '97 Civic
(http://media.honda.co.uk/car/owner/m...df/23-a96.pdf),
that would most likely lead back to the ECU connection. The regulator
actually controls the voltage across the field coil of the alternator,
which of course affects the voltage produced by the rotor coils. From
the diagram, it looks like the ECU also "injects" a voltage at the low
side of the coil, which would allow it to alter the delta voltage in
addition to the regulator (note: I have a good background in general
electronics, but am not trained specifically in modern automotive
charging systems, so some of this is just educated guessing).

A short in that ECU lead SHOULD'T affect the regulator directly, as
there's a diode there that would block any reverse current flow if the
ECU lead were to short to ground, but maybe the '98's alternator is
different - without that diode, a short could potentially fry the
regulator, allowing full voltage to flow through the field coil and
cause the rotor coil output to spike. Or it might not even be affecting
the regulator - just shorting that lead would have the same effect (then
again, if it's testing overvoltage on the bench, the regulator probably
is fried - damn).

So there you have it. Short of looking at a proper schematic of the
'98, my best guess is still a problem in the ECU. The cooked regulators
are a symptom, not the root of the problem.


I'd love to see a schematic of how the regulator itself is set up
inside, it would help the diagnosis.

"Matt Ion" > wrote in message
newsUhrg.129222$IK3.68382@pd7tw1no...
> Spdloader wrote:
>> "Spdloader" > wrote in message
>> . ..
>>
>>>Hi, I'm new to the group, but my daughter has a Honda now so I'll be
>>>lurking.
>>>I didn't find anything on this exact problem in a search so:
>>>
>>>Vehicle is a 1998 Civic DX 5spd.
>>>
>>>Dead battery prompted a test of the alternator, which wasn't charging at
>>>all.
>>>Replaced alternator, and externally charged battery overnight. The car
>>>started fine the next morning, and it worked fine for about 1/2 a day,
>>>charging between 13.8v and 14.2v, then the speedo quit working, then that
>>>evening the headlights were dim.
>>>
>>>Next morning, battery was weak again, I charged the battery for a while,
>>>then started it, but now there is a no charge condition again, verified
>>>with a Fluke meter at the battery, but not at the alternator.
>>>
>>>A brief check of the fuse block under the dash revealed a blown 10A fuse,
>>>Alternator / Speedo. Replaced it, had a charge at the battery, then blew
>>>the fuse when moving the vehicle in the driveway.
>>>
>>>I suspect the vehicle speed sensor has a bad connection or is
>>>malfunctioning. Any other ideas before I dive back in tomorrow?
>>>
>>>Thanks in advance!
>>>
>>>Spdloader
>>>
>>
>>
>> Alternator taken off and tested, charged 20volts, 20amps on the bench,
>> and voltage regulator bad.
>>
>> New alternator installed, worked perfectly for 5 mins, then fuse blew,
>> and I'm right back to square one.
>>
>> Gonna go have a Mt. Dew now.
>
> So something else is killing the voltage regulator(s - 4 of them now!),
> which then of course isn't regulating the output properly. Going by the
> schematic I found for the '97 Civic
> (http://media.honda.co.uk/car/owner/m...df/23-a96.pdf),
> that would most likely lead back to the ECU connection. The regulator
> actually controls the voltage across the field coil of the alternator,
> which of course affects the voltage produced by the rotor coils. From the
> diagram, it looks like the ECU also "injects" a voltage at the low side of
> the coil, which would allow it to alter the delta voltage in addition to
> the regulator (note: I have a good background in general electronics, but
> am not trained specifically in modern automotive charging systems, so some
> of this is just educated guessing).
>
> A short in that ECU lead SHOULD'T affect the regulator directly, as
> there's a diode there that would block any reverse current flow if the ECU
> lead were to short to ground, but maybe the '98's alternator is
> different - without that diode, a short could potentially fry the
> regulator, allowing full voltage to flow through the field coil and cause
> the rotor coil output to spike. Or it might not even be affecting the
> regulator - just shorting that lead would have the same effect (then
> again, if it's testing overvoltage on the bench, the regulator probably is
> fried - damn).
>
> So there you have it. Short of looking at a proper schematic of the '98,
> my best guess is still a problem in the ECU. The cooked regulators are a
> symptom, not the root of the problem.
>
>
> I'd love to see a schematic of how the regulator itself is set up inside,
> it would help the diagnosis.

I wonder if there is something else in the circuit, i.e. sensors such as O2,
or something that could be shorted somehow.

I think I'll let it rest over the weekend and do some fishing. I think I can
do that right.

Spdloader

Spdloader wrote:
> "Matt Ion" > wrote in message
> newsUhrg.129222$IK3.68382@pd7tw1no...
>
>>Spdloader wrote:
>>
>>>"Spdloader" > wrote in message
om...
>>>
>>>
>>>>Hi, I'm new to the group, but my daughter has a Honda now so I'll be
>>>>lurking.
>>>>I didn't find anything on this exact problem in a search so:
>>>>
>>>>Vehicle is a 1998 Civic DX 5spd.
>>>>
>>>>Dead battery prompted a test of the alternator, which wasn't charging at
>>>>all.
>>>>Replaced alternator, and externally charged battery overnight. The car
>>>>started fine the next morning, and it worked fine for about 1/2 a day,
>>>>charging between 13.8v and 14.2v, then the speedo quit working, then that
>>>>evening the headlights were dim.
>>>>
>>>>Next morning, battery was weak again, I charged the battery for a while,
>>>>then started it, but now there is a no charge condition again, verified
>>>>with a Fluke meter at the battery, but not at the alternator.
>>>>
>>>>A brief check of the fuse block under the dash revealed a blown 10A fuse,
>>>>Alternator / Speedo. Replaced it, had a charge at the battery, then blew
>>>>the fuse when moving the vehicle in the driveway.
>>>>
>>>>I suspect the vehicle speed sensor has a bad connection or is
>>>>malfunctioning. Any other ideas before I dive back in tomorrow?
>>>>
>>>>Thanks in advance!
>>>>
>>>>Spdloader
>>>>
>>>
>>>
>>>Alternator taken off and tested, charged 20volts, 20amps on the bench,
>>>and voltage regulator bad.
>>>
>>>New alternator installed, worked perfectly for 5 mins, then fuse blew,
>>>and I'm right back to square one.
>>>
>>>Gonna go have a Mt. Dew now.
>>
>>So something else is killing the voltage regulator(s - 4 of them now!),
>>which then of course isn't regulating the output properly. Going by the
>>schematic I found for the '97 Civic
>>(http://media.honda.co.uk/car/owner/m...df/23-a96.pdf),
>>that would most likely lead back to the ECU connection. The regulator
>>actually controls the voltage across the field coil of the alternator,
>>which of course affects the voltage produced by the rotor coils. From the
>>diagram, it looks like the ECU also "injects" a voltage at the low side of
>>the coil, which would allow it to alter the delta voltage in addition to
>>the regulator (note: I have a good background in general electronics, but
>>am not trained specifically in modern automotive charging systems, so some
>>of this is just educated guessing).
>>
>>A short in that ECU lead SHOULD'T affect the regulator directly, as
>>there's a diode there that would block any reverse current flow if the ECU
>>lead were to short to ground, but maybe the '98's alternator is
>>different - without that diode, a short could potentially fry the
>>regulator, allowing full voltage to flow through the field coil and cause
>>the rotor coil output to spike. Or it might not even be affecting the
>>regulator - just shorting that lead would have the same effect (then
>>again, if it's testing overvoltage on the bench, the regulator probably is
>>fried - damn).
>>
>>So there you have it. Short of looking at a proper schematic of the '98,
>>my best guess is still a problem in the ECU. The cooked regulators are a
>>symptom, not the root of the problem.
>>
>>
>>I'd love to see a schematic of how the regulator itself is set up inside,
>>it would help the diagnosis.
>
>
> I wonder if there is something else in the circuit, i.e. sensors such as O2,
> or something that could be shorted somehow.

I don't think there'd be anything else specifically on that wire... the
sensors would have their own connections to the ECU.

> I think I'll let it rest over the weekend and do some fishing. I think I can
> do that right.

Heheh... like I said, try checking with a wrecker, see if you can get
another ECU for cheap, and swap it in.

Okay, forget what I wrote before about how the alternator works... I had
it kinda back-assward.

I found a great site detailing how alternators work, and how their
regulators work, and how it all works together. I'll hafta go back over
all this and re-think it a bit, but in the end, it still sounds like
it's probably something related to that ECU lead - either a short, or a
problem with the ECU itself - that's cooking the regulators.

Anyway, for anyone else who's interested:
http://www.1stconnect.com/anozira/Si...alternator.htm

"Matt Ion" > wrote in message
news:8Flrg.129888$IK3.93664@pd7tw1no...
> Spdloader wrote:
>> "Matt Ion" > wrote in message
>> newsUhrg.129222$IK3.68382@pd7tw1no...
>>
>>>Spdloader wrote:
>>>
>>>>"Spdloader" > wrote in message
. com...
>>>>
>>>>
>>>>>Hi, I'm new to the group, but my daughter has a Honda now so I'll be
>>>>>lurking.
>>>>>I didn't find anything on this exact problem in a search so:
>>>>>
>>>>>Vehicle is a 1998 Civic DX 5spd.
>>>>>
>>>>>Dead battery prompted a test of the alternator, which wasn't charging
>>>>>at all.
>>>>>Replaced alternator, and externally charged battery overnight. The car
>>>>>started fine the next morning, and it worked fine for about 1/2 a day,
>>>>>charging between 13.8v and 14.2v, then the speedo quit working, then
>>>>>that evening the headlights were dim.
>>>>>
>>>>>Next morning, battery was weak again, I charged the battery for a
>>>>>while, then started it, but now there is a no charge condition again,
>>>>>verified with a Fluke meter at the battery, but not at the alternator.
>>>>>
>>>>>A brief check of the fuse block under the dash revealed a blown 10A
>>>>>fuse, Alternator / Speedo. Replaced it, had a charge at the battery,
>>>>>then blew the fuse when moving the vehicle in the driveway.
>>>>>
>>>>>I suspect the vehicle speed sensor has a bad connection or is
>>>>>malfunctioning. Any other ideas before I dive back in tomorrow?
>>>>>
>>>>>Thanks in advance!
>>>>>
>>>>>Spdloader
>>>>>
>>>>
>>>>
>>>>Alternator taken off and tested, charged 20volts, 20amps on the bench,
>>>>and voltage regulator bad.
>>>>
>>>>New alternator installed, worked perfectly for 5 mins, then fuse blew,
>>>>and I'm right back to square one.
>>>>
>>>>Gonna go have a Mt. Dew now.
>>>
>>>So something else is killing the voltage regulator(s - 4 of them now!),
>>>which then of course isn't regulating the output properly. Going by the
>>>schematic I found for the '97 Civic
>>>(http://media.honda.co.uk/car/owner/m...df/23-a96.pdf),
>>>that would most likely lead back to the ECU connection. The regulator
>>>actually controls the voltage across the field coil of the alternator,
>>>which of course affects the voltage produced by the rotor coils. From
>>>the diagram, it looks like the ECU also "injects" a voltage at the low
>>>side of the coil, which would allow it to alter the delta voltage in
>>>addition to the regulator (note: I have a good background in general
>>>electronics, but am not trained specifically in modern automotive
>>>charging systems, so some of this is just educated guessing).
>>>
>>>A short in that ECU lead SHOULD'T affect the regulator directly, as
>>>there's a diode there that would block any reverse current flow if the
>>>ECU lead were to short to ground, but maybe the '98's alternator is
>>>different - without that diode, a short could potentially fry the
>>>regulator, allowing full voltage to flow through the field coil and cause
>>>the rotor coil output to spike. Or it might not even be affecting the
>>>regulator - just shorting that lead would have the same effect (then
>>>again, if it's testing overvoltage on the bench, the regulator probably
>>>is fried - damn).
>>>
>>>So there you have it. Short of looking at a proper schematic of the '98,
>>>my best guess is still a problem in the ECU. The cooked regulators are a
>>>symptom, not the root of the problem.
>>>
>>>
>>>I'd love to see a schematic of how the regulator itself is set up inside,
>>>it would help the diagnosis.
>>
>>
>> I wonder if there is something else in the circuit, i.e. sensors such as
>> O2, or something that could be shorted somehow.
>
> I don't think there'd be anything else specifically on that wire... the
> sensors would have their own connections to the ECU.
>
>> I think I'll let it rest over the weekend and do some fishing. I think I
>> can do that right.
>
> Heheh... like I said, try checking with a wrecker, see if you can get
> another ECU for cheap, and swap it in.

Thanks for all your work and help Matt, I'll get to a salvage yard right
after some fishing.
Spdloader

Spdloader wrote:

> Thanks for all your work and help Matt, I'll get to a salvage yard right
> after some fishing.
> Spdloader

Oh yeah, fishing definitely comes first!

"Matt Ion" > wrote in message
news:Ifnrg.126796$iF6.118171@pd7tw2no...
> Spdloader wrote:
>
>> Thanks for all your work and help Matt, I'll get to a salvage yard right
>> after some fishing.
>> Spdloader
>
> Oh yeah, fishing definitely comes first!

It does after the week I've had!

Later,

Spdloader

Spdloader wrote:
>
> "Kevin McMurtrie" > wrote in message
> ...
> > In article >,
> > "Spdloader" > wrote:
> >
> >> With the fuse replaced, at idle, the new alternator charges 13.9v, as
> >> soon
> >> as you rev the motor the tiniest bit, the alt/spd fuse blows.
> >>
> >> I'm guessing, I've got yet another bad alternator.
> >>
> >> Spdloader
> >
> > It sounds like you have the output and regulator wires mixed up. The
> > alternator's regulator should draw more power at idle and never blow a
> > fuse.
>
> Um, nope, sure don't. Didn't read the whole thread, did ya?
>
> Spdloader

----------------------------------------

You probably covered this already, but look at the sixth article in this
page (regarding the Honda ELD):

http://www.asaaz.org/canyonauto/techtips.htm

'Curly'