So last November the battery light came on in my TSX along with a high pitched whirring noise. Took it to a mechanic friend who said the alternator was bad and he replaced it. About a few weeks ago(5 months later) my battery light is starting to flash off and on occasionally while I'm coming to a stop or slowing down. Doesn't seem to every come on while accelerating. Mentioned it to my mechanic and even though the voltage outputs were good he replaced the alternator for free just to be safe. After about a week the light will randomly flash again while I'm stopping or slowing down. He said my battery is still good but is there something else that could be causing this? Could my car just not like the brand of alternator. He uses a rebuilt alternators from Carquest.

 

My car had the similar symptoms last year (whirring noise) - it was the alternator. I had it installed at a dealership who used OEM parts. I think the entire bill was around $300 - for something critical like an alternator, you should probably just go OEM and have it done at the dealership.

 

Sounds like the belt may be slipping. The tensioner may not keep it tight enough at low speed to allow the alternator to produce proper voltage. Food for thought.

 

Also possible to have a slipping bushing in the crankshaft pulley/harmonic balancer. The rubber bushing gets loose and outer pulley slips instead of driving the accessory belt. Check is to make a radial mark across the face of the crankshaft pulley assy. If marks get displaced from each other the bushing is slipping.

good luck

 

I'd start with the simplest thing, which is to check the tensioner as Simba said. It would also probably be the easiest/cheapest thing to do.

 

A mechanic would be needed to check the tensioner?

 

Anyone willing to take a picture of exactly where I would mark it?