battery light, flashing oil light, no rev counter....

[Pickard1]

Hi,
My battery light has come on as well as the oil pressure light flashing and the rev counter stopped working at the same time.

I have a P reg golf III diesel estate (non turbo)

I have checked the auxiliary belt, it seems to be all in order. I have 12v across the battery, but not the 13-14v I would expect if it was charging properly. Also I cant get a decent voltage from the altenator to the battery negative or engine block.
A few weeks ago I fitted a new water pump that was faulty, this shredded the aux belt. When the belt snaped the oil pressure light flashed as well as the battery light, so it seems that this flashes when the altenator is not charging??
I have now replaced the water pump and aux belt so it looks like the altenator is knackered to me - would this cause the rev counter to fail as well or could there be another problem? Obviously in all the messing around with the water pump the altenator has been off and on a couple of times so it seems reasonable that a 12 yr old altenator might have got damaged during all of this...
Is there anything else I can do to confirm its the altenator before I spend 100 odd quid on a new one? Also I have heard about the voltage regulator, is it worth trying this first, the actual altenator doesnt seem to be seized or anything....?

Thanks in advance....

[kenney]

Everything points to the alternator,most of the VAG alternators have an easy replaceable voltage regulator,and some regulators,you can in fact replace the brushes.BUT in most cases the commutator(slip rings)are worn,you can check them when you remove the regulator,then you will be needing a replacement unit.

[Pickard1]

Thanks for your help.
I decided to bite the bullet and get a whole new unit. I needed to get it fixed today and it seems the aftermarket places (GSF, ECP, Unipart...etc...) dont sell the regulators so I would have had to have waited for Monday for the ******** to open.

It has fixed my symptoms.
I'm guessing that something in the oil pressure and rev counter electrics requires them to have a very stable voltage to work....?

[theevilone666]

The rev counter works off of an electrical loom???? thats interesting...but surely if that does then so would the speedometer??

[Pickard1]

I dont really understand it, but if the altenator isn't spinning as well as the battery light you get no rev counter and the oil pressure light flashes, even though I am sure neither system is driven directly of the auxilliary belt.
even though the problem is fixed occasionally I get a little bit of belt slip and while its slipping the oil pressure flashes and the rev counter drops to zero.

[theevilone666]

If you are getting the squealing belt slip syndrome....find the tension adjuster and tighten it up a little...

[Pickard1]

aghhhh......I didn't have any problems with this since October when I changed the alternator, then today my symptoms have returned.

Even though the belt is properly tensioned the altenator has stopped charging again. Alongside this I am getting an illuminated battery symbol, a flashing oil symbol and no rev-counter as per the previous occasion. The battery definitely isn't charging as it is refusing to start now.

Could this be a bad alternator? Its only 6 months old....or is there something else on my car that is causing this to happen. It seems a bit of a coincidence and I want to be sure before I go and spend another 70 quid on a new alternator.

Does anyone know why the alternator would effect the rev counter and oil light....is it to do with the voltage regulator?

Are there any checks I can do with the voltmeter to confirm if the alternator is no good. For instance if the voltage regulator was broken would I see a lumpy voltage, or even an ac voltage.....?

[theevilone666]

Check the connection located between the alternator and the fans for the radiator......it may just be the connection is slightly loose or rather not connected properly......