Q: Alternator Fault

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I have a late model 2008 Audi A4 (euro). For the last few months I've been having constant trouble with a fault in the car. For no reason the car started with a message on the dash "Alternator Fault. Battery not charging". Sometimes the fault will go away from a few minutes to even a day after turning off and restarting the car. I've had the regulator and brushes in the original unit replaced, I had another alternator fitted, a new regulator fitted in that unit and a brand new battery fitted. None of these attempts have stopped the fault from returning. The latest fix, fitting a new regulator in a used alternator has worked fine for the last two weeks but today the warning light has returned and left me having to jump start the car to get going again. The light is now appears immediately after starting. I find it hard to believe that it could really be an alternator problem given that I had refurbished the original unit, and refurbished and fitted another one with the same results.

My car has 190000 miles.
My car has a manual transmission.

You will need to check the one way clutch pulley on the alternator to see if it operates as it should.

First remove the belt. Then using a plastic or non conductive blade and put it in the alternator rotor to hold the alternator from turning. Now turn the one way clutch pulley. It should turn easy in one direction and not turn at all in the other. If the pulley turns in both directions or binds at all, then it is defective and should be replaced.

If the pulley works as it should then you will need to inspect the wire harness to the alternator and the fuse box for any loose or damaged connectors/wires and repair them as needed.

If you need help with these checks, get some help from a professional mechanic who can diagnose this warning light firsthand and make the necessary repairs.

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