mattyacura

Hi all,
I'm new to posting, but I've been a part of this forum for some time and I really appreciate this resource.

About my issue: I have a 2005 TL base model with 140k. A month or two after replacing my battery, my battery light came on. I assumed it was the alternator and took it in, had it tested, and it was indeed bad, so I replaced the alternator with one from Advance.

Soon after replacing the alternator though, the battery light would briefly come on once every week or so, but only during deceleration and only for a second or two. Knowing that Advance would only take a return on their battery if it was showing "Bad" on their test, I decided to live with it for a bit. Also, I was, and am not entirely sure it's the alternator. I've checked the grounds, and they all look good.

But recently, the battery light started coming on much more regularly during deceleration, and last night it came on solidly and not only on deceleration. I'd had the lights, defrost, wipers, and radio on. Today however, it's back to coming on only during deceleration, but still basically every time. I'm thinking of upgrading the grounds anyway, but I'd rather fix this problem first before doing other things. Since it's doing basically the same thing it did with the previous bad alternator, I'm led to believe it's just a bad alternator and not the grounds.

My questions are:
1. Any ideas what this could be?
2. Will an alternator that is only intermittently defective test as "Bad?"
3. Is there any way to test to eliminate either grounds or bad alternator without removing the alternator again? I've got a meter, but I'm not the best at using it yet.
4. Is there a way to test whether or not the grounds are good?

Thanks in advance.

01acls

Check the cables for corrosion or defects. Its better to recondition them to ensure a full and complete flow of current.

Recondition as in free of oxidation on all contact surfaces.

Remove all cables when feasible and check for loose crimps and clean in a mild solution of water and baking soda.

The simple things we tend to over look and take for granted.

Check grounds by continuity test. However, thats not necessarily definitive bc amps require a load test. Hence the reconditioning.

Check the alternator on car with car at operating temperature and engine running. Alternator should be putting out 15V at 2000 rpm at alternator. Again not definitive due to unknown amp out.

Unfortunately more times than not you get what you paid for... aftermarket part or reconditioned part. If its to good to be true it probably is.

There is a reason why some people paid extra for oem parts, its not because their rich or cheap. It is from bad experiences and they don't have time for stupid stuff like this.

Keep safety in mind when working with a running engine. Be aware of moving belts. No loose clothing or rags in hand.

Be safe.

BTW I think its a defective alternator or alternator regulator.

mattyacura

I thought I'd give some closure to anyone dealing with the same issues, although I'm not sure it really provides the answer. I took the alternator out and it tested as fine, which I suspected it would since the battery light only came on intermittently. Per the guy at the store's advice, I broke one of the spades off of the connection and they replaced the alternator for me. I also bought some 6 ga. wire and added a couple of grounds. So far, almost a month later, there's been no light.