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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”
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.
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…
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.
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”
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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