Hi,
We have had an ongoing saga with our 2010 XC60 T6. Three years ago we had a charging failure light go on while traveling, had it towed to a local shop and had a new alternator put in. Worked fine for about 18 months and then periodically but just temporarily we would get the charging failure light to go on. Never long enough to where a garage could assess while it was malfunctioning. About a 2 months ago, it died when my wife tried to drive it, I put in a new battery that didn't solve the message but gave it enough juice that we could drive it to our local garage. Our mechanic replaced the pully because it seemed to be seizing up along with a few other parts while the serpentine belt was out. Worked find for about a month.

A few weeks we got a low beam failure warning that was flashing erratically like you would see with a short (the low beams seemed to both be working) and then shortly after, we go the charging failure message again. I took a multi meter to it and sure enough it was not generating any additional charge at first but then suddenly it was cranking 14+ volts like it should. This week the issue is back again. I can see all the belts turning but am getting the low beam failure again (although again the low beams seem to be working) and then eventually the charging failure.

With battery, alternator, and serpentine pulley all replaced, I'm at a loss on what else it could be. Could a bad pully have burnt out my new rebuilt alternator from 3 years ago?

Thanks and any feedback would be appreciated.

 

Update. I did go out and start it up and revved it up to high rpms and the issue seems to have gone away for now. So who knows. Still welcome any feedback.

 

If your charging failure light comes on - that means the voltage in the battery is higher than the voltage from the alternator with the engine running. In other words - the alternator is not charging. Your 2010 T6 alternator has a overrun/one way clutch that allows the alternator to keep spinning when the engine slows down. A common problem is that the alternator clutch seizes and loosens the drive gear causing the alternator to not spin/charge. Then a shop decides the alternator is bad, (they don't notice it's not spinning) replaces the alternator (transferring the old seized pulley to the new alternator), and eventually figures out the old alternator is not really bad when the new one does not charge, but hey it's installed, they can't return it and you have agreed to buy it. In the process they tighten the loose drive gear and that solves the problem. Temporarily.

Shortly afterward the same thing happens because the alternator pulley is still seized and pulls the drive gear loose again. And you get a charge warning.

"Serpentine belt was out". The serpentine belt drives the water pump and ac compressor (power steering also on some cars). The alternator is on the other side of the READ assembly. (rear engine accessory drive) So the serpentine belt has nothing to do with the alternator.

Not quite sure what when on with that repair! What pulley was replaced? There are actually 2, One on each side of the READ. One for the alternator (actually mounted onto the alternator) and one for the serpentine belt and they both can seize and need to be replaced.

Your low beam failure - which headlamps do you have? HID or Normal H11? H11 has connection problems at the bulbs. The connectors melt and create a bad connection. The HIDs have a ballast and work like a flourescent bulb, there is no filament in the bulbs - those can be a bad ballast, connection or just an old bulb - like an old fluorescent bulb.

 

Thanks for this info. I did replace the headlamps and that failure warning has disappeared so it was just coincidence that the two warning occurred at the same time. I can see that the the belt on the alternator is spinning. The charging failure warning has come on two more times while the car was idling but then went away. I can reach down to the alternator when the engine is not running and pull the belt towards me fairly easy so it doesn't feel seized up.