Intermittent charging issues (FSI)

markhux33

Member
Hi all,

I've been a long time viewer of the forum but this is my first post.

I purchased a 2004 FSI in July 16. Very shortly after buying it I had the red battery (charging) light come on the dash permanently. After some fault finding with a multimeter it looked like there was no output from the alternator at all and the battery was slowly draining (culminating in the engine cutting out).

After taking the car to A2 Cars they sent the alternator off to an alternator shop and replaced it with a reconditioned unit. This immediately solved the issue and it continued to work flawlessly for the next 12 months (~10000 miles).

One day in July 17 when I went to start the car it turned over very slowly and wouldn't fire at all. After charging the battery on a charger over night I tried again with the exact same result. I left it another day and tried again and this time it eventually sputtered into life after about 5 seconds of turning over slowly. Everything appeared fine and all the lights cleared. Over the next week I started getting intermittent red battery light on the dash again (which generally cleared with revs).

Eventually the light came on steady once again and coincided with the power steering failing. It was again sent to A2 cars who sent the alternator back to the service shop. They said that alternator had been damaged by water ingress and replace it with yet another reconditioned part. This made no difference and A2 cars tried cleaning one of the earth connections which seemed to cure the problem.

I then drove the car for another two weeks before the light once again came on and the power steering again failed. My next port of call is to check the earth strap behind the headlight and inside the passenger foot well, check the positive battery lead in the plastic housing and check the loom where it runs through the firewall.

I'm sure that both alternator and battery are in top condition so I strongly suspect a wiring short or bad earth somewhere on the car. From browsing this forum it looks like there could be a myriad of corroded wires so I'm open to any suggestions.

I'll keep you updated with what I find.

Cheers,

Mark
 

Attachments

  • A2.jpg
    A2.jpg
    296.7 KB · Views: 226
Have you tested for current leakage when ignition is off? Have you tested the alternator output? The earth behind the headlight is a well known issue though remember a visual inspection is not suitable, ours looked fine though was severely corroded behind the heat shrink. Is your bonnet drip and catcher fitted correctly as the alternator doesn't appreciate being dripped on(speaking from experience).
Lastly, what age is the battery and what distances are you driving as short winter runs knock hell out of your battery.
Best of luck, I had a LWB landy that started so sporadically that I always had to park on a slope (finding people to shove it wasn't always easy). :)
 
I need to have a look at current leakage too, would you just measure the current at the battery terminals with the ignition off? The battery was replaced in December so is virtually brand new and is fully charged. The alternator output was good when tested at the garage. I'll check it again but I don't think that is the issue.

Good call on the drip catcher. Last I checked it was installed correctly but maybe it's somehow leaking onto the alternator.
 
Is there a guide on how to remove the alternator ?
Mine should be replaced too... :(
 
If you get the charge light comming in intermittently it can be due to the regulator (which is a removable module on the alternator and only costs a fraction of a replacement alternator). So if the output is ever up to the right level (~14.5v), then you can assume the alternator is good as they don't tend to fail intermittently. If the voltage varies and drops into the 12s & low 13s then there is a strong change the regulator is on it's way out.
 
Thanks, I also considered changing the regulator alone.
I don't know if this can be done with the alternator in situ. It seems there are screws under that can maybe not be undone...
I got a permanent red light on the dash. All the time. I will check the voltage.
I think it has come due to the car staying outdoor and beeing driven very little. A2 is too small for the enlarged family, I have a big 7-seater Mercedes now.
So, moist having caused the failure ?
 
I've still not had any luck, it seems that the regulator may well be at fault. I think that will be the next thing to change.
 
Mark - if you haven't already, I would strongly suggest getting an ODBII reader if you don't have a suitably older PC laptop with VCDS connector and Rosstech's software. 3 years back I had recurrent EVAP (ghost in the machine) errors bringing on the engine light on my bigger Audi that cost me 40 quid a go even at the independent place for a checkup to clear the engine light - I bought a reader off Amazon for 24 quid and saved myself probably 300 quid since. My reader even as a simple one can check things like alternator voltages vs. revs and check for error codes - and could give you a big indicator towards what the problem might be (particularly when people here with experience ask more technical questions where the onboard diagnostics may already have the answer). 1.6 FSI?

Bound to be something trivial but insidious - as a Tdi owner my observation in the last few months has been that FSI ownership is like masochism, but mostly without the happy ending.
 
  • Like
Reactions: fbi
I would recommend one of the bluetooh ODB-II adapters and the "Torque" s/w for Android (not sure whether there is an IOS version). Total cost <£20.
 
. .....

Bound to be something trivial but insidious - as a Tdi owner my observation in the last few months has been that FSI ownership is like masochism, but mostly without the happy ending.

Hi Robin,

Got a bit confused by the last bit, surely the masochist would be happy, lol.

Seriously though, as a FSI owner, is it fair comment when from what I see the electrical gremlin in question could occur in any A2 variant?

Andy
 
Last edited:
Thanks for the advice. Yes I think having a look at the OBD readout would be a good idea. Maybe that is the next thing to take a look at. Up until then the last 18 months of FSI ownership have been golden. It's awesome when it works :).

The alternator is definitely not charging the battery now so the light isn't spurious. If you drive it for long enough the engine will cut out and the DIS dies when the battery gets low :O. Obviously not a great idea for the poor battery.
 
Hi it sounds like your alternator has failed or at least part of it. However one bit I got from your post is that the second alternator was diagnosed as water ingress damaged. Well I strongly recomend you remove the bonnet and clean out the rubber water/debris traps on the back of the bonnet. They often get full of rotting leaves and this allows water to leak onto random areas of the engine. The rubber bits just pull off.
Cheers mike
 
Thanks Mike,

I think they were relatively clear last time I looked but it's a good shout.

Sent from my Pixel XL using Tapatalk
 
Mike you were right about the alternator.

After getting the wiring diagrams off erWin and going through everything with a multimeter I narrowed it down to something internal to the alternator itself as it had a good supply, earth and field and the car started fine when the starter motor and alternator share a common positive and earth (through the mounting).

I decided to just bite the bullet and buy a new Bosch alternator (036903024D) from carpartsinmotion for £188 and change it myself. That way at least I knew I had a brand new working genuine part.

Upon removing the alternator it was obvious that the part fitted previously at A2Cars was a totally different size and shape. It didn't have any obvious part number or branding on it but it was also quite badly corroded for what was supposedly a reconditioned unit.

Anyway I fitted the new alternator which came with the new pulley and hey presto the problem is solved. The charge is now normal again and all lights out!

Sometimes the most obvious solution is also.the right one :). I guess placed too much faith in the "reconditioned" parts that I had been told were fitted.

Sent from my Pixel XL using Tapatalk
 
Back
Top