Alternator warning light on: advice, please

[scandalxk]

Evening All,

 

My 2007 Octavia Scout has been sluggish in starting for a week or so, in the cold weather, and yesterday the alternator warning light came on, and stayed on while I was driving.  It took me about an hour to get home.  Today, just now, it started fine.  It's a little bit warmer today.  The alternator warning light stayed on again, though.

 

So if there was actually a problem with the alternator I would expect the battery to have gone flat during the drive home yesterday afternoon.  Can the alternator warning light also indicate that the battery itself is getting a bit tired?  Or could it indicate some other problem?  And how can I tell which it is?

 

Many thanks as always,

 

scandalxk

[J.R.]

2 hours ago, scandalxk said:

if there was actually a problem with the alternator I would expect the battery to have gone flat during the drive home yesterday afternoon.

 

Not so, assuming yours is a diesel engine they can cover a couple of hundred miles in daylight if you are aware of the problem and dont use electrical equipment unnecessarily and still restart the next day.

 

I had the alternator light come on (MK1 Octavia) on the M25 travelling to Dover to return to France, I took an educated risk and carried on, left the engine running at customs checks etc, it restarted at Calais and took me a further 95 miles, a total of say 150 miles the last hour with the lights on and it still restarted the next day.

 

Your warning light does what it says on the tin, tells you the battery is not charging, put a charger on it and investigate the fault, dependant on how many miles the car has done it could be worn brushes like mine was, a very easy cheap repair.

Edited 16 December, 2023 by J.R.

[J.R.]

A petrol engine will have less autonomy due to the ignition system, a later diesel less autonomy than an earlier simpler one.

[scandalxk]

Thanks for your detailed reply, J.R.  One thing you haven't addressed is whether the alternator warning light (an illuminated picture of a battery) could also indicate a problem with the battery rather than the alternator?  I just dug out all the receipts and the last time I seem to have bought a battery for the car was in January 2018, nearly six years ago.  It had a three year warranty...😆 Perhaps I have identified the problem? 😊

[J.R.]

1 hour ago, scandalxk said:

One thing you haven't addressed is whether the alternator warning light (an illuminated picture of a battery) could also indicate a problem with the battery rather than the alternator?

 

No, it will have no bearing.

 

I understand your logic though regarding the image.

[seriesdriver]

If you have a multimeter and know how to use it start the car and see what voltage you have at the battery you should be able to work out if the alternator is charging or not.

[scandalxk]

On 16/12/2023 at 18:29, J.R. said:

... it could be worn brushes like mine was, a very easy cheap repair.

 

OK, I decided as the battery is six years old I would change it anyway, and see what happened.  Warning light is still on.  So now I am thinking about the alternator, and J.R. said the worn brushes would be "a very easy cheap repair".  I can't find an appropriate video on YouTube or instructions anywhere on Briskoda - can you help me with that?  It's a Bosch alternator, see picture.  I did find this video which is quite good but I think he says it applies only to alternators up to 2001: my car is 2007.

 

Alternatively I could change the alternator, and I found this one (the second one down, 14V for climate control models) at £104.  Perhaps this would be a reasonable alternative, if I can't do the brushes?  It can't be that difficult to fit...can it?

 

Cheers,

 

scandalxk

[J.R.]

7 minutes ago, scandalxk said:

So now I am thinking about the alternator, and J.R. said the worn brushes would be "a very easy cheap repair".  I can't find an appropriate video on YouTube or instructions anywhere on Briskoda - can you help me with that? 

 

Sorry no, you will have to use your eyes and common sense like I did.

 

The brushes will come as part of a replacement regulator assembly which is at the back under the cover that you have photographed, you will probably be able to get another couple of thousand miles out of yours by freeing them off or tweaking the wire braid to give them a little more travel whilst you await the new regulator.

 

You have not given your location, spare parts for alternators are not 'were not) available in my country but freely available in the UK.

[scandalxk]

I'm in Carlisle, Cumbria.  I'll try in a motor factors, or look on Ebay.  Thanks.

[Breezy_Pete]

I think the regulator for that alt has genuine part number 06F903803B. 

That may help you to cross-reference it to a Bosch part number.

[scandalxk]

20 minutes ago, Breezy_Pete said:

I think the regulator for that alt has genuine part number 06F903803B. 

That may help you to cross-reference it to a Bosch part number.

OK, so are you thinking I could replace just the regulator, and not have to faff about soldering new brushes into the existing regulator?  That hadn't occurred to me.  Google tells me the part would be around £22.  Is it likely I'd be able to do that without removing the alternator from the car?  And, further stupid question: what do you mean by "genuine part number" for the regulator?  Surely that would be the same as the Bosch part number, given that it is to fit a Bosch alternator?

[J.R.]

2 hours ago, J.R. said:

The brushes will come as part of a replacement regulator assembly

 

[J.R.]

1 hour ago, scandalxk said:

Is it likely I'd be able to do that without removing the alternator from the car?

 

Looking at the photo I would say highly likely but each engine installation is different, on mine it was easier for me at the time with limited tools available to do it in situ rather than remove the alternator, I had to do some of it by feel though.

[Breezy_Pete]

I meant the genuine VW-Group part number, in the same sense that the genuine (VW) part number for your whole alternator is 06F906023F, as seen in your photo. 

I could work out the correlation via a couple of pages in the parts catalogue, 'alternator versions' and 'alternator and single parts'.

 

Two points of interest now that I'm looking with morning eyes on a larger screen. "Made in GB" on the main part number label. 😲

And just above and to the left of the barcode you can make out some of the Bosch part number info of the regulator/brushpack itself, I think. BR14 - H, and then below that F 00M 145 316, possibly

A different view might reveal all of that latter bit, which is how Bosch identify their brushpack/voltage regulators in detail. 

 

Be careful if you do try to change it in situ; the thick output cable connected to B1+ is fused, but it'll be a fairly heftily-rated strip of metal, so if you forget to remove battery negative first, and short that to earth, there will be a big flash and crackle before that fuse pops.

[krisp1]

To clarify VAG group have their own part numbers for their parts that they buy.

In this case Bosch have their own part numbers for the assembly and numbers for all the components.

Yes Bosch had an alternator factory at Miskin near Cardiff just off the M4. It closed in about 2012 and moved production to Eastern Europe.

[J.R.]

VAG buy entire assemblys from several manufacturers, examples being a Bosch or Valeo alternator or a Sanden or Valeo AC compressor, they will both have the same VAG part number and also their own manufacturers part numbers.

 

If you want a regulator pack or AC pulley shear plate VAG will say "Computer says No!", you have to buy the complete unit, the manufacturers may well sell the service parts, if they dont there are scores if not hundreds of aftermarket manufacturers who do.

[Breezy_Pete]

Actually VAG will say, yes of course you can order an 06F903803B regulator; that'll be £116.16 including VAT.

 

Oh, and different brands of alts do tend to have different part numbers or suffixes. Not sure on compressors but would suspect the same to be true.

Edited 19 December, 2023 by Breezy_Pete

[scandalxk]

20 hours ago, J.R. said:

 

Sure, but they are also available as independent brush sets.

[scandalxk]

13 hours ago, Breezy_Pete said:

I meant the genuine VW-Group part number, in the same sense that the genuine (VW) part number for your whole alternator is 06F906023F, as seen in your photo. 

I could work out the correlation via a couple of pages in the parts catalogue, 'alternator versions' and 'alternator and single parts'.

 

Two points of interest now that I'm looking with morning eyes on a larger screen. "Made in GB" on the main part number label. 😲

And just above and to the left of the barcode you can make out some of the Bosch part number info of the regulator/brushpack itself, I think. BR14 - H, and then below that F 00M 145 316, possibly

A different view might reveal all of that latter bit, which is how Bosch identify their brushpack/voltage regulators in detail. 

 

Be careful if you do try to change it in situ; the thick output cable connected to B1+ is fused, but it'll be a fairly heftily-rated strip of metal, so if you forget to remove battery negative first, and short that to earth, there will be a big flash and crackle before that fuse pops.

Thanks.  Understand now re. part numbers...probably.  Yes, that "Made in GB" caught my eye too, but only because it is unexpected.  I assume this means it is likely to be a replacement part?  Surprising, because I have had the car since it had done 39,000 miles so it must have been replaced before then.  And yes, that power cable is too thick to be cavalier with!

 

Ah, just read @krisp1's post above...perhaps it could be an original part.

Edited 19 December, 2023 by scandalxk

[J.R.]

2 minutes ago, Breezy_Pete said:

Actually VAG will say, yes of course you can order an 06F903803B regulator; that'll be £116.16 including VAT.

 

OK, times have changed then, or maybe way back when I could not find a single seller in France of alternator spares (they were all trotting out the line that it was illegal) it could have been that VAG did list the part, but it would have been and still is the last place on earth I would go to!

 

France does have some really crazy protectionist laws, its illegal for anyone to make or sell body parts except the manufacturers and they extend that to mirrors, bumpers etc etc, just over the border in Belgium there are outfits that will sell you pattern part bumpers, mirrors etc sprayed to your colour code and fitted while you wait for 30% of the price of the bare unpainted and unfitted main dealer part in France to which they add the bodyshop time, paint and fitting labour, it comes out around 85% cheaper to cross the border.

[Breezy_Pete]

Date code on part number sticker says it's original, week 26, 2007.

[krisp1]

The part numbers generally are unique for a part from a specific manufacturer. The logistics scheduling systems struggle to manage to order from two suppliers with the same part number. The SAP system at Bosch could not manage that.

As I stated Bosch had the plant in the UK suppling all over Europe so it was original fit. When I visited it was certainly making parts for BMWs that were only built in Germany, amongst many variants.

[scandalxk]

Hi Everyone, thanks and update:

 

First, thanks to everyone who replied.  As always with Briskoda, I learned a lot more than I expected, and I was once again struck by the helpful, well-informed and friendly tone of the discussion.

 

Second, update.  I wanted to do the job myself but ran out of time, needing the car at short notice over Christmas.  So instead of spending twenty-odd quid on a new regulator, I had to spend £290 😥 on getting a new alternator fitted.  Bloody Norah.

 

But now I know better for next time...assuming I ever own an IC-engined car again.  Thanks once again for your input.

 

Kind regards,

 

scandalxk