battery charging light on dash flickers on at high revs ?

Post by **rikpal** » 30 Sep 2008, 21:40

just started finding that the charging red light flickers on & off when revs are high e.g over 80 kph in 5th gear. the belt is new, the tension seems fine, can this be an indicator of an alternator problem? or just a slipping belt. :

doesn't seem to be causing any problems at the moment, but don't want to run in to battery problems over winter. at the very least the red light is very annoying as I've justfixed the dash illumination.
thanks for the help

Post by **kevtherev** » 30 Sep 2008, 21:55

Check the wiring and connections first, particularly the one to the starter motor
check that belt tension is correct ( 10mm movement either way )

Alternators have regulators/brushes and this is the one part of an alternator that will have intermittent faults. So depending on what the fault is it may be worth changing it especially if no other problems can be found.
regulators are relatively cheaper than a replacement unit.

Post by **kit** » 30 Sep 2008, 21:58

Check you have fitted the right belt.

Post by **ashman** » 01 Oct 2008, 06:56

If you can access the brush pack on your alternator take these out and check their condition. If they are knackered then you can replace them easily. If they are in a poor way and you don't change them it will eventually kill the alternator.

Post by **lloyd** » 01 Oct 2008, 07:44

as ashman said, check brushes. Worn brushes loose contact at high rpm and will cause this

Post by **ashman** » 01 Oct 2008, 07:59

Yep! If the brushes are really worn then at higher speeds they will struggle to make a good contact. If you can take the brush pack out of your alternator then it's worth a quick check to see.

Post by **rikpal** » 01 Oct 2008, 09:11

Thanks for that guys,will try & get to the brushes this weekend.

Post by **Ian and Lins** » 01 Oct 2008, 12:27

First tip to check wiring is dead important. Visually looked OK on mine (I had same prob) but didn't do a continuity check. Turned out to be internal break in wire as insulating sleeve was fine. Bought and fitted a new alternator before I found that out!

Post by **rikpal** » 01 Oct 2008, 16:31

Got brushes out 1 of which looks very worn, 1/2 length of other which seems a bit weird.
any way, cleaned up the brushes & oil & gunk from the alternator & put back together. All seems to be working fine now. But I have ordered new brushes & will put in this weekend. so much better than the new alternator option

Post by **kevtherev** » 01 Oct 2008, 16:32

ashman wrote:Yep! If the brushes are really worn then at higher speeds they will struggle to make a good contact. If you can take the brush pack out of your alternator then it's worth a quick check to see.

thats what I said

are my posts invisible?

Post by **Hypnovan** » 02 Oct 2008, 09:20

Who said that? Did someone say 'that's what I said' ? Forum ghost methinks.

Website · Post by **CovKid** » 02 Oct 2008, 12:49

I'll throw in food for thought here. In the early 80s I had a bug windscreen wiper motor pack up because of brushes and the manual said something along the lines of "head to your nearest VW dealer and purchase a new brush plate" - which I did. Only it turned out that VW had stopped doing brush sets and could only offer me a new unit at the equivalent of £175 now.

On the basis that the brushes were being used in a 12v system and not particularly big, I went to a lawnmower shop and chap found a pair that were very close but marginally too big. I honed them down with wet''n'dry - perfect fit and only 15p.

The reason I mention this is that with cars, it often pays to think laterally when you're presented with expensive options. A good friend of mine illustrated this point with a phrase I've never forgotten:

"If you want car parts go to a bike shop and if you want bike parts, go to a car shop" - its a point we should all bear in mind.

The simplicity of these vehicles allows far more scope for inventiveness. The same cannot be said of modern cars which are constructed on a plug n play basis but no 'fix' solution other than swapping out modules.