C270 Battery/Alternator warning

[mymelt8]

Hello all, I'm getting getting the Battery/Alternator warning message at regular intervals after the engine is warm. Mostly under light load but it can happen on the overrun also.I've just had a B service and the garage ( indy ) could not pick the fault up on on their diagnostic. Odd considering that it shows as a fault when the ignition is off. Apparently all the charging/battery voltages are OK.
C270,2002, 122K.
Any thoughts? Many thanks.

 

[television]

All faults are recorded, if you have a side lamp bulb blown, that will be there in the memory.

Was the test done on STAR

 

[mymelt8]

I'm not sure. I'm going to nip down to a Bosch service centre and get them to have a look. I would have thought all faults would be recored too. I faild to mention that there is very dry / rough sounding bearing noise from down there also.
Will report back later.
Thanks

 

[mymelt8]

Went to the Bosch - so called - specialist and after some humming and haring the recon'd that it might be the pulley. The alternator was charging at 14.2 volts. My question now is, can a faulty pulley result in a under charging situation? My guess is that they fail on, rather than slip. Also, could it be the regulator, and can that be replaced? Sorry to keep banging on but it seems to me that there is far more knowledge on the forum than most garages I've been too lately and I don't want to be cornered into replacing the whole alternator.
Many thanks
Adam

 

[Cole@MBS]

The regulator is the most common fault with your model, easy to replace, the pulley needs a special tool to replace it!!