intermittent charge issue

Bernie Benz b.benz at
Sat Aug 22 16:14:09 PDT 2009

The blue wire is not/ does not supply alternator field coil current.  
It is a ground source for the no charge idiot light when the  
alternator is not supplying voltage to its rectifier array. As such,  
it is an initial mA current source to the stator windings which may  
or may not be necessary to trigger initial voltage build up,  
depending upon the residual magnetism of the rotor.

I have found the problem in one such alternator as being a poor  
crimped connection in the stator winding 3 phase  “Y“ connection.  
Soldering solved the problem.


On Aug 21, 2009, at 9:51 AM, Geraint Lloyd wrote:

> Is it not charging at all or just not charging enough?
> Had an 18 month old recon one fail with what must have been a short  
> in the
> exciter coils It was drawing 280mA as opposed to the <150mA-ish  
> that it was
> supposed to through the blue wire. It was charging, but not enough  
> to keep
> up with the drain of the AC, rad fan and monster, monster  
> headlamps.......
> New voltage reg made no difference. I now have a spare for the Golf2
> Have had new stuff not respect the "excellence comes as standard"  
> rule and
> fail out of the box, but that was more Lucas than Bosch. Nothing is
> impossible...
> I assume that you have checked or replaced the blue wire to the  
> connector on
> the chassis rail by the water bottle?
> Also i once managed to install a voltage reg on the 200 using the  
> wrong set
> of threaded holes on the back of the alternator meaning that the  
> brushes too
> far away from the slip rings... Moral: use a good flashlight if you  
> are
> doing it with the car on its wheels in the dark........
> Geraint
> -----Original Message-----
> From: 200q20v-bounces at [mailto:200q20v- 
> bounces at] On
> Behalf Of feelstranger
> Sent: 21 August 2009 11:46
> To: 200q20v at
> Subject: intermittent charge issue
> Folks, I'm experiencing an intermittent charge with a newly  
> installed Al179x
> alternator.  (Bosch remanufactured)
> Primarily after some time on the highway - and then after "cooling  
> off" for
> a while (on the side of the road, or rest area) it works for some  
> time -
> though that seems to be getting more variable.
> Swapping the voltage reg. had no change, and I confirmed that there  
> was no
> charging  after the warning light came on.
> Anyone ever have a faulty "new" alternator?
> Could it be something else?   I'm relatively confident it is not an
> intermittent igniter circuit.
> Thanks
> Nat
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