1.6D alternator not charging - batt. light on dash not lighting.

[epowell]

The alternator is supposedly new...
Last year it was working and charging perfectly.
Now with a new battery in there, KEY-ON and the battery light at the dash is not lighting. Start engine and alt. is not charging.

What to do?

The alt. has a single 3-way connector out the back which has 2 large contact holes and 1 smaller hole. Starter battery charge 12.6V and the 2 large holes read 12.5V with KEY ON. The smaller hole read 12.2V.
The small blue wire from the batt. + terminal leading to the dash, reads 12.2V also.
The alt. house IS grounded.

Not sure what else to check and/or what to do... any ideas?

Thanks!
Ed
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[valvecovergasket]

its been a while, but from my mk1/mk2 days if the little alt lamp itself goes bad, you wont complete the excite circuit to start charging the alternator.

the light not coming on with the key suggests thats the case.

id start there
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gone, but not forgotten: '83 tdi westy - swap thread

[MarkWard]

Disconnect the blue wire from the alt. Key on it should have battery voltage. If you ground the blue wire with the key on, light in dash should light. Report back.
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[epowell]

[MarkWard]

I'm sure crazyvwvanman will answer this better, but a simple explanation is the alternator D+ terminal acts like a ground when the key is turned on. At the same time 12 volts is supplied from up front that "excites" the alternator into charging. At that point, the D+ terminal is no longer acting like a ground and 12 volts is fed back up the blue wire. Having 12 volts on both sides of the bulb, causes it to go out.

This explanation is to help you understand roughly what is going on, but is by no means complete or accurate.

Yes, I would suspect the voltage regulator or the alternator has an internal problem.
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[crazyvwvanman]

Yes, try removing the regulator/brush assembly from the alternator. That is likely where the problem is. Check the brushes for length and surface, etc.

But as nasty as the alternator looks in the photo I'd think about a different one at some point.

Mark

[epowell]

[epowell]

Thanks everyone for the help... I am now back in Czech and didn't have time to finish fixing this issue while in Vancouver... It will have to wait until next August.
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[epowell]

[epowell]

So I managed to remove the VOLTAGE REGULATOR...
...and immediately noticed that the electrical contacts were corroded - so I cleaned them all up and in-installed the VR in the naive hope that that would fix it...
Went to the dash, KEY-ON, and still no Batt.light

Any ideas?

Thanks
Ed

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www.edwardpowell.com

[MarkWard]

I’m going with my first test. If the light lights when you ground the blue wire I think it’s time for another alternator. You could buy a new regulator and try that first. If no luck, you have a spare regulator for the future. Buy an alternator and install it. Or find a local auto electrical shop to rebuild yours using your new regulator. As you can tell, it’s also the brush pack.

There is a remote possibility the blue wire is connected to the wrong terminal. It should be on the D+ terminal. Some diesel alternators have a W terminal for a tach reference.
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[epowell]

[epowell]

PS ---
OH, ONE MORE THING!!!!!!
I had reconnected the battery after the first V.REG check... then when going out to check the v.reg again, I noticed that the V.REG was pretty warm! Almost hot!!!
WTH? ....some kind of 'short'?
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[MarkWard]

Those molded plugs did fail internally. VW did away with them. The alternator has constant power, but at rest I would expect it to not be hot to touch.

You are welcome to take it apart. Not sure about repair parts. There are specific diodes and rectifiers. There are automotive electrical shops that rebuild alternators and starters. My hunch is a reman will be quicker. Cip1.ca or maybe Rock Auto if they have a
Distributor in Canada.
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[epowell]

why would the v.reg. get hot?? This does NOT seem normal!
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[MarkWard]

[crazyvwvanman]

A new regulator assembly with brushes is about $15-20 delivered to me. Don't know about your side of the border.

A slightly higher output voltage one is about the same price.

Examples:

https://www.ebay.com/itm/Voltage-Regulator-3523710...Swp-RaawdR

https://www.ebay.com/itm/Voltage-Regulator-fits-19...Swnxxd4AnU

Mark

[RawUmber]

If I'm not mistaken, the regulator module should stay cool with key on, because it's not regulating. When the engine (and alternator) is running, it likely will warm up because it's regulating. If it’s getting hot with just key on, I think you and Mark have isolated the problem.

FYI, you can buy new brushes, vreg, the whole module, not to mention a new alternator. I've read people on here suggest buying a lifetime warrantied alternator from a franchise that has stores where you tend to travel.

I like Mark's DIY abilities, but to be a little safer (yet much slower), maybe leave the engine off and free spin the alternator pulley (belt removed) by hand if you're going to go that route of sanding the copper. I agree though, the outer copper shaft ring surface looks less than perfect.

[epowell]

cleaned up the copper (fingers still intact) [actually I did it by proxy]
and cleaned everything else....
but still no BATT LIGHT

I'll go now to open up that black tape to see what lurks under it all...

V.reg, starts to get warm again just as soon as I connect the battery [no KEYON, but KEYOFF and battery hooked up] What's going on with THAT? Is it normal?

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[RawUmber]