Battery Light On and Off

[Scottymon]

Noticed this flag up on the dash whilst driving today, came up a couple of times then didn't reappear in the 45mins home.

Here: http://www.begoodtoyourvw.com/service/dashboard-indicator-lights/ suggests it's a charging problem; I've scanned it and nothing was recorded... which I would've thought the system would have... any suggestions, or this 100% a failing alternator?

[Scottymon]

Is the alternator a big job?  Are there any DIY's about... it would seem logical to take the Intake Manifold off first --- assuming of course this isn't duff battery or something else.

[doylebros]

Check all your connections visably and physically on the :-

battery

engine bay fuse box

chassis earth straps

Then moving on to multi meter testes  for both voltage and current( if you have access to one)!

[Scottymon]

I'll dedicate some time to checking this all out over the Bank Hol. yes have multi-meter, cheers for the input

[doylebros]

Last job removing the alternator - engine bay fuse box fusible links corrosion would be my choice since its an intermittent fault?

[Scottymon]

I hear ya, I always fear the worst, lol

[Scottymon]

Checked it all, seems good, not shown up again, after a good little blast today, who knows, eh?

[doylebros]

That's cars for you - tricky little blighters - pleased it's gone though!

[Scottymon]

Cheers mate, good for now, will keep an eye on it... no doubt show it's head again and leave me stranded in the depths of winter.

[xjay1337]

I had this problem on my TDI, and it was the alternator. The bearings were going/went. You could hear it on idle rattling.

I suspect it's the same thing here. Check for noises from the alternator. Vagcom scans are not always the answer.

[Scottymon]

Thanks, I'm not ruling it out; idle seems quite smooth ATM, for TFSI at least,
ESP. After changing for some Nology plugs yesterday, I've checked the VW workshop manual online, the job doesn't look too bad if it needs doing at some point.  
Just wondering' would a duff battery cause this?  Guess the colder winter months will show up that too.

[xjay1337]

Generally not. If the battery is able to sustain starting the car, once the car is starteed then 99% of the electrical systems are powered directly from the alternator.
The light comes on when the battery is not being charged.

[Scottymon]

Probably early signs then, may look out for a refurbed one and keep it incase... It's noteworthy that I had xenons on, AC on low at full chat and HU pumping out, lol, fair amount of load right there I would think, also in slow moving traffic at that point... I'll give it another test.

[xjay1337]

It shouldn't matter about the load. 

I have two 400cc compressors powering my air ride, which take quite a hefty load - more so than the radio/AC etc.  Even with night with the lights on, my radio on, iPod in glovebox (on charge) with the AC on  and no battery lights so I would suggest something is wrong.

[Scottymon]

Hmm, this doesn't look good, I'm getting all sorts of errors now... this morning I had a MAF error (forget exactly what), then this afternoon the EPC light came on and reduced power.

Scan shows:

000546 - Angle Sensor 2 for Throttle (G188): Signal Too Low

Cleared it but came straight back up again.

Weird isn't it, I've had a years worth of faults a week before my MOT and now this... I'm very much hoping it doesn't require a new Throttle body.  Does seem odd these different errors that pop up and never return, perhaps a wiring issue?