I've had my Pd105 Elegance since Feb, and pretty much since I got it it's had this issue...

Most mornings I'll get the battery light on when I start it, and if it's cold it'll come on during the day too, it'll go after a quick press on the accelerator.

When running at idle, all lights go dim and brighten constantly. Doesn't matter if it's all the lights on just 1 interior light.

VCDS brings up an under voltage fault for all locking modules, but nothing else.

Apparently the alternator was changed last year, but I've since learned it wasn't.

So, before I go out and buy a multimeter to check what the voltages are, what connections can I check, and where are they? I'm wondering if it's as simple as a corroded terminal somewhere. Some people have also mentioned a broken sensor wire?

If it is the alternator, is there anything I can do to help it keep going a little while longer until I can afford to replace it? Not sure if electrical contact cleaner might help? When I can do it, and if it needs replacing, are there any larger amp alts that'll bolt straight on? Next year I'm hoping will bring some nice powerful audio into the car so I may aswell sort the supply if I can...

You can check the alternator output by putting your multimeter across the battery terminals set to 20 volts dc and start the engine with light on, should be about 14.5 volts.  

 

There were some alternators with a clutch system in the pulley, on the passats it was a common failure, working only sometimes.

 

There are spares available for the alternator , ie brushes and rectifier pack. that ebay thingy was were I got them for a Passat.

it may be just dirty brush holders and therefore sticking brushes not applying enough pressure to the "com"

A specialist Auto Electrical place (often with a BIG Bosch sign) should do this if you don't want to delve too deeply.

With a bit of luck, may also be more amenable to a bit of light repairing rather than the automatic "Its gorra be renoowd".

Hmmmm.....may have to have a good look at it then! Multimeter will be bought this week and I'll find a guide to see what I'm actually looking at! If I find nowt, it'll go to a pro! Hoping it is just a little corrosion or something sticking, can't be doing with any issues with Christmas arriving!

Cheers guys!

Try engine earth. Was always a classic on pfl octavias

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Will have a look at that then, thanks!

Where abouts is it on the 105?