About Battery Warning Light, Do You Know Something About it?

[polotim]

Hello there,

I have a Mustang 2008 GT and have the battery warning light coming on and off intermittently for the past 3 months or so.

Alternating-current generator was replaced 2 years ago and battery less than 1 year ago.

Car starts up and drives just fine and never had any issues until today.

This morning when I went to put the key into the run position, I noticed that all the analog dials swept to the max position and back to zero. Car starts up just fine. I drove it about 1-2 miles and parked.

Came back to the car, key into run position and the dials swept through again. But when I tried to start, the starter clicked and loss all power to the car. No dome lamps, no trunk lights, nothing. Like there wasn't a battery in the car.

Popped the hood, and disconnected the negative cable from the battery. I reconnected the negative cable to the battery and the power came back on in the car. Key back in run position, dials sweep and car starts up just fine.

Drove another 1-2 miles and parked for about an hour. Went back to car, key in run position, dials do not sweep and starts up just fine. Drove 3-4 miles and the battery warning light came on for a bit, then went away and came back on again.

From my Google search, I found a lot of people saying to "check the grounds". I really don't know what that means.

Any ideas? Help! Thanks a bunch.

 

[kimyong]

You won't see the corrosion that we are talking about. It makes a clear movie that will cause this exact problem.

The fact that you said you took your negative clamp off then put it back on and it started says that's the first place to start.

That generally shows you have the corrosive layer there cause when you pulled the clamp and put it back on it would have scuffed it a lil.
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[CorollaTom]

Electrical issues are particularly hard to troubleshoot by email. To properly troubleshoot this kind of problem, begin with the battery. You can get it tested at Autozone or Advance Auto for free. If okay,

 

[CorollaTom]

• Electrical issues are particularly hard to troubleshoot by email. To properly troubleshoot this kind of problem, begin with the battery. You can get it tested at Autozone or Advance Auto for free. If okay, move to the alternator - it can be tested at Autozone and Advance Auto, too. Just because the alternator was replaced only 2 years ago does not mean it is fine - if it was a rebuilt unit when you put it in, it probably contained used components like the voltage regulator. I have a 1991 Toyota Camry that experienced problems similar to yours-my rebuilt alternator contained most of the original components (a common rebuilt in. dustry practice)-but it was a faulty internal regulator that produced symptoms like the one you describe. Changing the regulator inside the alternator housing solved my problem.
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• If the alternator tests good too then look for corrosion at the battery terminals and cable clamps