Trying to determine if I have a dying battery, or a failing alternator. Last week I sensed a bit more effort to start the car - caught, but just didn't seem normal. Then a couple of days later I noticed volts at around 13.5, again not the norm. Today, driving home from work, I noticed the volts move down to just under 12 volts. Got home, took a voltmeter to the battery which read 12.31 volts.
Is there a way for me to determine whether it's the battery or the alternator? I don't have a plethora of tools and equipment, and will plead ignorance anyway. I tried to check acid level in the "window" on the battery, but it was tough to get a good view of it due to its position in the trunk, and I didn't want to disconnect the battery to move it.
Any thoughts/advice?
On a separate note (I think), I also experienced a kind of limp-mode acceleration from start as of this past w/end. Checked the rear brake lights, they worked fine. Then I did a scan and got the following fault code:
00526 - Brake Light Switch-F
20-10 - Implausible Signal - Intermittent
So I presume the brake switch down at the brake pedal needs replacement? Anyone have a part nbr?
Thanks for your help