Stuck

[Christopher Pollard]

Hey folks-

Having an alternator issue / alt warning light issue that I can’t figure out. My TD is based on a 74 VW. The alt warning light was disconnected when I picked it up and obviously the ammeter was showing a constant discharge.

The alternator is an external Voltage Regulator type and the brushes all seem good. The D+ lead goes to the alt warning light and to the voltage regulator. The other wire on the light goes to the acc side of the ignition switch. The fixture is a solid rubber fixture with no apparent ground as you would expect if it were in a dash.

Problem is I get no light in key on mode, nor do I get a light when the car is running. Ammeter is still showing discharge and the B+ post on the alternator shows same voltage as the battery (11.56 by the time I was done tinkering tonight). The light works when tested from the + to – post on the battery so I know the bulb works and with the car running I have voltage across the terminals inside the light socket.

I would think if the alternator or voltage reg was crap I would at least get a light.

I am at a loss. Anyone have any ideas?

VW based CMC 52 TDr “Miss Gertrude” AKA “Gerty”

[Gregg Strain]

Is your alt light a led? If so, it will not work. Must be an incandescent and is essential to make it charge. There is a way to use led’s, but it is very involved. I have noticed with my Bosch alternator, that when I first start the car, I need to bump the throttle to get the system “woke up”. Here is one link with a diagram.

https://www.google.com/search?q=alternator+wiring&ie=UTF-8&oe=UTF-8&hl=en-us&client=safari#imgrc=wkZUiHiuUZO-8M:

[edward ericson]

I think you need to excite the field windings in your alternator. I had the same symptom when I put the Suby in Bridget.

Here’s a vid showing how it’s done with a Delco GM one.

Here’s a Samba discussion on topic for our stuff:

https://www.thesamba.com/vw/forum/archive/index.php/o-t–t-488081–.html

And yeah, don’t use LEDs for everything what’s wrong with people? Those little incandescents will work for 20 years at least…

[Gregg Strain]

Yes, it is true about residual charge on the windings.  That is the purpose of the charging indicator light circuit, however. A good article from SpeedyJim’s web page.

http://www.speedyjim.net/schem/mot_alt.htm

[Christopher Pollard]

edward ericson wrote:

I think you need to excite the field windings in your alternator. I had the same symptom when I put the Suby in Bridget. Here’s a vid showing how it’s done with a Delco GM one.

I am using an incandescent bulb – the original bulb was blown when I got the car.

Trying to figure out how excite the winding on the Motorola alternator I have. B+ wire to the field terminal?

I have wired the alt lamp directly to terminal 15 on the coil and still get no light nor any charge – even at close to 3k RPM.

For sake of full disclosure, I am a moderate mechanic and a crappy automotive electrician LOL  – you get a sucking chest wound, I can fix you with no problems, give me an issue such as this and I am damn lost.

VW based CMC 52 TDr “Miss Gertrude” AKA “Gerty”

[edward ericson]

I can’t remember how I got mine to work. I remember it was an accident, so probably I grounded the wire to the GEN light or something.

Again, this was the Subaru engine (and alternator).

If I knew what to do I’d tell you. When I don’t know what to do I just Google and then start, ya know, trying stuff…

http://c34.org/bbs/index.php?topic=9451.0

http://shoptalkforums.com/viewtopic.php?t=135956

Sometimes, no matter what you do and how little you know, it’s not your fault. Sometimes it’s just a bad part that ain’t work.

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