Annoying Generator Light

Harry Smith wrote:

> On Mar 7, 7:38 pm, Speedy Jim > wrote:
>
>> Try this:
>>Ground the Blu wire with key On. (Just the Blu wire end,
>>not spliced to anything.) The GEN light should come on.
>>
>>If that works, splice a long hunk of loose wire to the Blu
>>end and connect other end to D+.
>>Light should be On and, if you measure, voltage at D+ should be
>>nearly Zero.
>
>
> Jim,
>
> Okay, I've finally gotten back to this problem. My tinkering was
> rudely interupted by a burned out igniton condensor.
>
> I got some reading with my multimeter. With key on, engine off:
>
> D+ to ground: 1.17V
> B+ to ground: 10.5V
> Gen Light terminal to grnd: 1.2V
> and for comparison...
> Speedo backlight to grnd: 9.8V
>
> With engine running at low idle:
>
> D+ to ground: 13.3V
> B+ to ground: 11.8V
> Gen Light terminal to grnd: 13.3V
> and for comparison...
> Speedo backlight to grnd: 11.2V
>
> At a low idle (such as with a cold engine) the gen light is very dim,
> barely on. At a fast idle or while driving the gen light is bright.
> The voltage at B+ goes up some at higher RPMs, but I've not seen it
> get much above 12.5V any time I've checked. I'm frankly amazed the
> battery gets charged at all with readings this low, but I've been
> driving it for three months now and no problems. Maybe you'll be
> able to read more into this...
>
> Thanks,
> Harry
>


Quote: "At a fast idle or while driving the gen light is bright."

Measure the D+ voltage under these conditions.
I don't see how this could happen (normally).


Also, double check the polarity of battery voltage
and the B+, D+ voltage. If using a digital meter,
look for the (-) sign in the reading.

Something smells here.

On Mar 14, 11:49 am, Speedy Jim > wrote:

> Measure the D+ voltage under these conditions.
> I don't see how this could happen (normally).

Yeah, me neither. Voltage at D+ goes up to 14-15 volts with the
engine reved up.

> Also, double check the polarity of battery voltage
> and the B+, D+ voltage. If using a digital meter,
> look for the (-) sign in the reading.
>
> Something smells here.

I know about polarity and all those readings were positive voltage.
This has me questioning my sanity...

Thanks,
Harry

Harry Smith wrote:

> On Mar 14, 11:49 am, Speedy Jim > wrote:
>
>
>> Measure the D+ voltage under these conditions.
>> I don't see how this could happen (normally).
>
>
> Yeah, me neither. Voltage at D+ goes up to 14-15 volts with the
> engine reved up.
>
>
>> Also, double check the polarity of battery voltage
>> and the B+, D+ voltage. If using a digital meter,
>> look for the (-) sign in the reading.
>>
>> Something smells here.
>
>
> I know about polarity and all those readings were positive voltage.
> This has me questioning my sanity...
>
> Thanks,
> Harry
>
>

If D+ goes to 14-15V, then B+ *should* go very close to that.

Still, 15V shouldn't be enough to light the GEN light brightly
(15 - 12V = 3V).

I wonder if you have some bad diodes in the alternator...

That could cause differing voltage between D+ and B+ and
affect meter readings.

Gottum o'scope?

Jim

On Mar 14, 2:46 pm, Speedy Jim > wrote:
> If D+ goes to 14-15V, then B+ *should* go very close to that.
>
> Still, 15V shouldn't be enough to light the GEN light brightly
> (15 - 12V = 3V).

Except the voltage up at the dash is usually more like 9-10 volts.
Would 5 or 6 volts be enough?

> I wonder if you have some bad diodes in the alternator...
>
> That could cause differing voltage between D+ and B+ and
> affect meter readings.
>
> Gottum o'scope?

No, I'm afraid not. Is it possible to have bad diodes and the
alternator still function?

Thanks,
Harry

Harry Smith wrote:

> On Mar 14, 2:46 pm, Speedy Jim > wrote:
>
>> If D+ goes to 14-15V, then B+ *should* go very close to that.
>>
>> Still, 15V shouldn't be enough to light the GEN light brightly
>> (15 - 12V = 3V).
>
>
> Except the voltage up at the dash is usually more like 9-10 volts.
> Would 5 or 6 volts be enough?
>
>
>> I wonder if you have some bad diodes in the alternator...
>>
>> That could cause differing voltage between D+ and B+ and
>> affect meter readings.
>>
>> Gottum o'scope?
>
>
> No, I'm afraid not. Is it possible to have bad diodes and the
> alternator still function?
>
> Thanks,
> Harry
>

Yes, bad diodes producing only a part of the waveform.

Your meter can then give unpredictable readings which won't
square with the observations.

See if there is an auto alternator shop nearby that can do testing.

Jim

Actually if you have an open diode, it will affect the alt.'s out put.
Typically an alternator will put out around 14.5 volts DC. With all the
electonics on newer cars it has to put out that much to run all the
electronic stuff and still charge the battery. Older cars with no
electronics "may" be more forgiving of that problem. However when my Ford
van had an open diode on the alt. it was just enough to keep just barely
enough charge to where it would start everyday and keep the battery charged
to bare minimum to keep it running. The output was about 11.5 volts. The
problem would show its self with night time driving with the winshield
wipers, headlights and A/C on. But I did mostly day time driving so it
didn't put as much of a strain on the electrical system so it took a while
for me to find out there was a problem..

BTW some alternator problems, open diodes are caused by jump starting
another car... some people just dont do it correctly, even though they
think they are. They think just hook up the cables and rev the crap out of
it and immediately trying to start dead car... BAM - current surge!! and
now the "good" car has just popped a diode. You need to let the good car
charge the dead car until there is a some what of a good charge on the dead
one, usually about 20 minutes at very least, depending on the dead cars
voltage level.

I did try to jump my completely dead '69 and it popped a diode in the Ford's
alternator... a quick stop at Auto zone and their tester confirmed that.
Thats how I know.



--
vwvwvwvwvwvwvwvwvwvwvwvwvwvwvwvwvwvw
dragenwagen
1966 Type I
http://www.ramva.org/dragenwagen
"Old VW"s don't leak oil, they mark their territory."
vwvwvwvwvwvwvwvwvwvwvwvwvwvwvwvwvwvw
"Harry Smith" > wrote in message
oups.com...
> On Mar 14, 2:46 pm, Speedy Jim > wrote:
>> If D+ goes to 14-15V, then B+ *should* go very close to that.
>>
>> Still, 15V shouldn't be enough to light the GEN light brightly
>> (15 - 12V = 3V).
>
> Except the voltage up at the dash is usually more like 9-10 volts.
> Would 5 or 6 volts be enough?
>
>> I wonder if you have some bad diodes in the alternator...
>>
>> That could cause differing voltage between D+ and B+ and
>> affect meter readings.
>>
>> Gottum o'scope?
>
> No, I'm afraid not. Is it possible to have bad diodes and the
> alternator still function?
>
> Thanks,
> Harry
>

On Mar 18, 9:56 pm, "dragenwagen" > wrote:
> Actually if you have an open diode, it will affect the alt.'s out put.
> Typically an alternator will put out around 14.5 volts DC. With all the
> electonics on newer cars it has to put out that much to run all the
> electronic stuff and still charge the battery. Older cars with no
> electronics "may" be more forgiving of that problem. However when my Ford
> van had an open diode on the alt. it was just enough to keep just barely
> enough charge to where it would start everyday and keep the battery charged
> to bare minimum to keep it running. The output was about 11.5 volts. The
> problem would show its self with night time driving with the winshield
> wipers, headlights and A/C on. But I did mostly day time driving so it
> didn't put as much of a strain on the electrical system so it took a while
> for me to find out there was a problem..

Hmm, very helpful. I'm used to "modern" cars with fuel injection
computers and the like, so a bad alternator is just bad. I have a
feeling this might be my problem. The battery has never really ran
dead on me, except when I did a lot of cranking on it trying to figure
out an ignition problem. All the symptoms you describe are there
though. Low voltage pretty much across the board, etc. Maybe I'll
take the alternator off and get it tested sometime this week. I just
noticed a rattle inside the fan shroud I want to check out too.

While we're on the subject, can you recommend any shops on the Gulf
Coast here that consistantly stock a good array of VW parts? I like
O'Reilly's for most purposes, but often they just don't have the old
VW stuff...

Peace,
Harry

Talk to Doug at Jus Bugs. he is located in Pass Christian, Down off Minge
Ave, He is an EMPI dealer. His shop is out of the way, and behind his
house, thats off the beaten path. But he does carry VW parts and can get
what you need. His website is http://www.jusbugs.com/index.html He also
builds engines... he built mine. Hope that helps.

--
vwvwvwvwvwvwvwvwvwvwvwvwvwvwvwvwvwvw
dragenwagen
1966 Type I
http://www.ramva.org/dragenwagen
"Old VW"s don't leak oil, they mark their territory."
vwvwvwvwvwvwvwvwvwvwvwvwvwvwvwvwvwvw
"Harry Smith" > wrote in message
oups.com...
> On Mar 18, 9:56 pm, "dragenwagen" > wrote:
>> Actually if you have an open diode, it will affect the alt.'s out put.
>> Typically an alternator will put out around 14.5 volts DC. With all the
>> electonics on newer cars it has to put out that much to run all the
>> electronic stuff and still charge the battery. Older cars with no
>> electronics "may" be more forgiving of that problem. However when my Ford
>> van had an open diode on the alt. it was just enough to keep just barely
>> enough charge to where it would start everyday and keep the battery
>> charged
>> to bare minimum to keep it running. The output was about 11.5 volts.
>> The
>> problem would show its self with night time driving with the winshield
>> wipers, headlights and A/C on. But I did mostly day time driving so it
>> didn't put as much of a strain on the electrical system so it took a
>> while
>> for me to find out there was a problem..
>
> Hmm, very helpful. I'm used to "modern" cars with fuel injection
> computers and the like, so a bad alternator is just bad. I have a
> feeling this might be my problem. The battery has never really ran
> dead on me, except when I did a lot of cranking on it trying to figure
> out an ignition problem. All the symptoms you describe are there
> though. Low voltage pretty much across the board, etc. Maybe I'll
> take the alternator off and get it tested sometime this week. I just
> noticed a rattle inside the fan shroud I want to check out too.
>
> While we're on the subject, can you recommend any shops on the Gulf
> Coast here that consistantly stock a good array of VW parts? I like
> O'Reilly's for most purposes, but often they just don't have the old
> VW stuff...
>
> Peace,
> Harry
>

"dragenwagen" > wrote in message
...
> Talk to Doug at Jus Bugs. he is located in Pass Christian, Down off Minge
> Ave, He is an EMPI dealer. His shop is out of the way, and behind his
> house, thats off the beaten path. But he does carry VW parts and can get
> what you need. His website is http://www.jusbugs.com/index.html He also
> builds engines... he built mine. Hope that helps.
>
> --

Minge Ave ?????

LOL

James

Juper Wort wrote:

>
> Minge Ave ?????
>
> LOL
>
> James
>
>
>

James,
Is that a UK funny?

T'other James


P.S. Never mind. I looked it up :-)