Alternator Regulator Circuit Board (V. Boring Thread)

[Joester]

Hi all,
My alternator doesn't work.
There is no voltage being generated on the three pin socket, no matter which pins I test between.
I believe the little regulator PCB that mounts on the side might be the most obvious reason, I have removed it to have a look...

There are two sprung carbon brushes that contact the armature inside the unit.
The inner one seems very worn, compared to the outer (right hand side) one, it is worn below the central slot/notch in the bush, does this mean it's knackered ?

How does the regulator couple to the three pin socket ? Back through the right-hand brush ?

There seems to be two live connections, and one ground connection (smaller pin), obviously I need a ground and earth connection from here to the battery, but where does the second live go off to ? And am I even correct about these pin-outs ?

lastly, I have read on previous threads that these regulator boards don't cost much (£10 ?) but where from, and what's the part number, unusually it is not on the component.

Any other info greatly appreciated.

Regards,
Joe

[mk1]

What type of alternator is it?.
You should have battery voltage (12 ish when the engine is not running) at the red wires and the small wire is for the warning light on the dash (blue/white?) and if you earth this wire, it should bring on the alt warning light. If the brushes are worn excessively a new regulator brush pack may fix your fault.
hope this helps.
Steve.

[carrie]

as far as i remmber an alternator need power to work so if its disconnected it wont work anyway. have you tried to test amps instead of volts for the alternator as this means it can still be connected.
an ameter goes inline with the power cable, not accross +&- terminals (you probably know this but i have seen it done may times before)

[black_cabbie]

The alternator needs to be exited to start charging.

Thats what the blue wire coming from the cluster does. When you start the engine and the revs go arround 1100 the cluster will send 12V through this wire to the alternator.

So what you need to do is connect the blue wire to a permant 12V and then measure. The inside of the alternator rarely goes bad. Its the voltage regulator that does and people spend silly money on a new alternator when its just a 10 quid item.

[carrie]

thanks black thought that was the case.
unrelated question now.
in your spec in your sig the bmw afm, is that referring to an air mass meter as opposed to afm as i am wondering why it was changed if not (just curiosity and also i am considering changing my air flo to air mass on my 6series bmw (m40 engine) to reduce the lag created by the air flap and if you have done these kind of things you might know how its acheived or where i can get the info (its running motronic if that helps)).

[black_cabbie]

Not to highjack the thread but yes, I've come to a point where the original AFM is restricting the airflow.

The problem is that its not that simple to install it. First of all you need to find a way to either keep your old airbox or switch to an open air filter (aka induction kit). Induction kit means hot air = less hp.
Then you need to adjust your fuel pressure. You will probably need an adjustable Fuel pressure regulator and all of these will have to be carefully tuned on a rolling road with the presence of a Wideband sensor to monitor to the air/fuel ratio.

On a standard 8V engine (up to 120hp) don't expect any gains. In fact you will get into more trouble trying to make it perfect. This mod should be done last (after cam,chip, manifold, p&p and 2L bottom).
Also anyone running Digifant 16V engine should definitely do this mod. Increases up to 11hp have been recorded.

PS. highjack off 

[Joester]

Good info, except I do not have a blue wire !
What do you mean by 'cluster' ?
On the alternator, there are three connections, please can you confirm which wires go where black_cabbie ?

If the alternator needs 12 V to start charging, then I would have thought that connecting up ground, and then the other two to the battery would stimulate the alternator to do its job ?

Where can I get a regulator from ?

Cheers.