I had the brake and battery lights on one day. Car drove fine.

Took it to the mechanic and they said my alternator is bad, so I had it replaced. The replacement was an after market, not OEM.

After that the lights went away and car drove fine.

Two weeks later, the lights came back on again. Only this time, it was not constantly lit, it was actually blinking. I drove around some more, and it went away. I took it back to the store where I replaced the alternator, and they checked it and said it's charging fine. It may just be "one of those things".

Another week gone by, the lights came back, and driving around, it went away.

In thinking back, I began to see a pattern. Each time this happened (including the first time), it happened after I had the car in idle for a long period of time. For example, one time I had to drop a friend off to a store and waited for him, while I had the air conditioning and radio on, the wait took a while, the other time, I was waiting to pick up my kid at summer camp and he took his time, both times I think it was a good 20 minutes or more while the car sat in PARK and I had the AC on, radio on. Then on the tail end of that the brake and battery lights came on.

The first time, the lights stayed on, and I had the alternator replaced.

The second and third time, they stayed on, and after I drove the car a bit (30 minutes) they went off. In fact, yesterday, I was watching the dash, the brake + battery lights on, I drove for about 10 minutes, then they changed from constantly lit up, to a gentle blinking, and when I stepped on the gas, the lights went off, when I let the foot off the gas pedal, the lights came back blinking, I did that for about another ten minutes then it went off for good.

Any ideas and suggestions what could caused this? A bad replacement alternator or something else?

Thanks in advance.

 

Was this an economy rebuilt alternator with 1 year warranty or a factory remanufactured unit with a lifetime warranty?

 

It's a rebuild with 1 year warranty.

 

Ya, I was wondering the same thing.

Make sure that you've verified the issue in writing. If it happens again I'd ask that the shop replace it under warranty. And I'd also suggest a better rebuilt unit (w/ a lifetime warranty, or at least a 2 year warr). Unfortunately, there are some very poorly rebuilt alternators (and starters) out there that aren't worth the box they came in.

That said, the issue could be due to the brushes "breaking in" (or wearing in). But it also could be signs of a soon to fail alternator...

 

If they go away after you increase the engine speed, I'd wonder is it's not a drive belt issue. Has the belt and tensioner been replaced?

 

My experience is those usually last 13 months.......or less.