Annoying Generator Light

Hi,
Since I've had my Bug, the generator light has been steady on. The wiring harness is a nightmare and since the battery has been getting
charged....simpler just to not get involved. It's always made me nervous though, and sure enough I recently had the belt come off due to an under-tight alternator pulley nut. The engine overheated before I realized anything was wrong, though thankfully it was just around town and not on the highway where some serious damage would have been done.
Realizing the error of my ways, I set out to fix that damn light. The car (a '74 standard) has had an alternator conversion, but whoever did it used some creative wiring. At the alternator, there is a large red/ white [1] AND a mysterious black wire [2] connected to the B+ terminal, and a mysterious red wire [3] connected to the D+ terminal. I tried connecting the hacked-off remains of the green wire to the alternator, but it did nothing.
Today I started monkeying with it some more and only after finding Speedy Jim's pages on the subject (highly informative, kudos to Jim) did things finally make sense. So, I spliced the blue and green wires from the regulator together and replaced the mysterious red wire on the D+ terminal with the green wire. Unfortunately, the light STILL doesn't work as it should.
I am fairly certain it is wired correctly, and the light does come on with the key, but stays on while the engine is running (however, its brightness is now directly related to engine speed, whereas before it was inversely related). I believe the problem is that with ignition on and engine not running, the voltage at the green wire is a measly 9-10 volts. The D+ terminal puts out 14-15 volts when running. I figure the wiring on the ignition side of the light is just so shoddy that there is enough "backflow" though the warning light to keep it on. The voltage at the red wire (that was previously connected to D+) is more like 11-12 volts, still not equal to the battery voltage but closer. Now that I'm thinking about it, I'm not even sure how the warning light was working before, as the blue wire wasn't connected to anything before I started...
So, anyway, does anybody think I have a chance at getting this working without rewiring the entire car? I fully intend to do that, and soon, but it would be nice to have the light working in the meanwhile. Also, I figure it probably isn't good for the alternator to be seeing that low of a voltage at the D+ terminal. Would I be better off just using the mysterious red wire until I rewire the whole damn thing and put these issues behind me?
Thanks, Harry
[1] The red/white wire appears to be correctly spliced into the battery and fusebox. [2] I have no clue where this goes. [3] No clue where this goes either, though it does not appear to be the red wire that used to go to the regulator, as that looks undisturbed under the rear seat.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Harry Smith wrote:

Sheeeesh! That's a lot to digest!
First, '74 came standard with an alternator (US), but it wasn't the one in there now.
The original was a Motorola with an *external* regulator mounted under the rear seat. The wiring looked like:
http://www.nls.net/mp/volks/schem/altreg.gif
When they "converted" yours to an alternator with *internal* regulator, there were some extra wires. The Grn and Brw no longer are neeeded. But the Red wire must still be connected to D+.
The Blu wire ends under the rear seat. It must be spliced to the skinny Red wire which went to the old regulator. That should make the dash "GEN" light work.
The skinny Blk wire on the B+ stud was for the Diagnostic Socket. See this article for all the gory details: http://www.nls.net/mp/volks/htm/plug.htm
Much more on this page of my web site: http://www.nls.net/mp/volks/htm/elec.htm
Post back with a progress report....
Speedy Jim http://www.nls.net/mp/volks /
"I have no use for a car which has more spark plugs than a cow has teats!" Henry Ford, when advised that Chevrolet was introducing a 6-cylinder engine.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I tend toward the verbose...

Huh...the blue wire must have been spliced to the small red inside the plug...sneaky of them and unobservant of me. That does explain a few things though.

It sounds like you are telling me to just hook it back up how it was before, but it wasn't working like that. The plug that went to the regulator was undisturbed. The green, brown, etc. wires at the alternator were clipped and unattached. There is a largish red wire (maybe 12 gauge) that was hooked up to the D+ terminal.

I've examined those diagrams closely, and I suppose I don't really understand why my setup should be any different than what is shown in the diagrams for a car converted from a generator. Is the warning light wired differently in my gauge than it would in a car that had a generator? This large red wire that was on the D+ terminal...where "should" it be wired to? What about the small red wire from the former site of the regulator?
In related news, I've been using wiring diagrams I found at http://www.thesamba.com/vw/archives/info/wiringt1.php However, the '73-up Std Beetle diagram doesn't really seem to match what I have. Which should be the closest? I just went and looked it up by VIN and it is in fact a '74.
Thanks, Harry
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

To avoid sounding stupid, I have seen the diagram that says "74-75", but the diagram itself says it is for Super and La Grande Bugs... I suppose that must be the one for me despite what it says...just my luck that the diagram I actually need is the hardest to read.
Harry
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Harry Smith wrote:

Last things first:
Download the diagram "1974-up Super Beetle only"
That will be correct for your car (they lied about the Super only).
Quote: "There is a largish red wire (maybe 12 gauge) that was hooked up to the D+ terminal."
That's not correct. I have no idea where they got that wire from. D+ should have the skinny Red wire that was part of the 3-prong plug (Red, Grn, Brw) and now cut off. As you note, the skinny Red is spliced to Blu back under the seat.
The GEN light in the speedo is the same for generator and alternator cars.
Jim
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Excellent...I feel like we're getting somewhere! Speedy as ever!
So really it doesn't matter if you splice the blue to the red or to the green, as long as the other end is hooked up to D+. Except now we're back to where we started in my first post...I've got the blue spliced to green, green hooked up the D+, and still the light is solid on.
Peace, Harry
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Harry Smith wrote:

HaHa. I missed the humor of the situation.
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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

It takes special people to find humor in electrical gremlins...

Tried that when I was messing around under the rear seat. The GEN light comes on when the blue wire is grounded, goes off when it is not.

That would be good to try, though I did check the green wire for continuity before I spliced the blue wire to it. I'm not sure exactly what you mean by the last part...are you saying with the generator light properly hooked up to D+, with the key on and engine off, there should be nearly zero potential between D+ and ground? That would make sense as that is the light's path to ground...but the problem isn't getting the light to come on, but making it go off when it should...hmm...
Well, looks like I've got something to do tomorrow. Thanks for all the help Jim, you are an asset to the group. I'll be back when I've got more to tell...
Peace, Harry
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
>. Thanks for all

indeed.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Harry Smith wrote:

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.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

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

I know about polarity and all those readings were positive voltage. This has me questioning my sanity...
Thanks, Harry
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Harry Smith 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).
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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

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

No, I'm afraid not. Is it possible to have bad diodes and the alternator still function?
Thanks, Harry
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Harry Smith wrote:

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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
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
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
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
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Minge Ave ?????
LOL
James
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Juper Wort wrote:

James, Is that a UK funny?
T'other James
P.S. Never mind. I looked it up :-)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.