Alternator warning light comes on at 2k revs - mk4 pd150

[Rob24]

Hi all,

 

My car (mk4 pd150) recently had to have a new alternator, auxiliary belt, and battery after the old alternator died. My issue isn't wholly fixed as after this work the alternator warning light comes on when my car goes over 2k revs. The garage told me I would need to get an auto electrician to look at the issue as they can't do that sort of work. I called the electrician and he seemed pretty confident that the garage fitted the wrong alternator. I rang the garage up and they checked the part and they are confident that it is correct. I have the auto electrician looking at my car on Tuesday but wondered if anyone else has any idea what is going on or if someone might have also had this issue?

 

Thanks

[Volkswagen Owners Club]

The first thing to do is check the battery voltage when the light comes on 
e.g. is it overcharging (above 14.5 volts maximum) when it goes above 2000 rpm
If so, then maybe the wrong alternator
If not then check all earths to the engine are in place and not disconnected or broken.

Otherwise last thing would be to check the over-running pulley is working okay (eg. only rotating one way and locking the other direction. If not then replace it with a new one