I apologize in advance if this topic has already been covered, there's a lot of pages to go thru.

I have an 01 V6 Tribute with 172k miles on it. I had the alternator replaced between 1-2 years ago.

Over this past summer, the battery light started coming on intermittently. Assuming it wasnt the alternator as it had somewhat recently been replaced, I bought a new battery. Everything was fine for a little while, then the light started coming on again. About 3 months into the new battery, my car wouldn't start one morning. I put a slow charge on it all day, then it wouldn't start again the next morning. I went back to the place I bought my battery, it tested good- but they offered to exchange for a new one if it would make me feel better, so I accepted.

The battery light stayed off for a few weeks, then started coming on again (in early October). Yesterday it wouldn't start again. I did a slow charge on it and it did start today. We looked at the wiring to the alternator and it had been clamped, I was told that doesn't usually work well. When we jiggled the wire to the alternator, the battery light would come on, so we figured the wire was the issue. Wire fixed- when jiggled, no battery light.

However, I drove it minutes later, and again the battery light came on. I took it straight to auto zone. They hooked up their little machine to the battery, said the battery and alternator both are fine.

Any ideas? I read somewhere that if the battery light isn't on when the alternator is tested, it will read good when in fact it may not be. Any help would be greatly appreciated!!

 

Also- the battery light comes on at random times (usually around 40mph), but today around 20 and usually when I let off the gas- but that hasn't been the case the majority of the time. It will come on while driving on the freeway. Sometimes it flickers, sometimes it stays on for a while.

 

Welcome to the forums!

One thing you can try is getting one of those cheap 12v power point (cig lighter), preferably one with a digital readout, voltmeters that you can keep track of to make sure there really is a problem going on as your driving (although having a second person watch it is not a bad idea ). The light comes on because the battery is now supplying voltage to the alternator to keep the magnetic field going, alternators (ones that I know of anyways) dont have permanent magnets so they cannot charge anything without voltage supplied to it to generate the initial field, once the alternator starts to generate its own current then it feeds a portion of that into maintaining its magnetic field, this is what turns your light off, the voltage coming out of the alternator "pushes" back on the voltage from the battery turning off your light. Basically when the light comes on it ONLY means that voltage is flowing from the battery through the light to the alternator, it does not 100% mean the alternator is dead, it just means current is going the wrong way, there could be a short in that wire somewhere.

Next up, like you have found, is loose wiring. Try removing and reinstalling the cables on the alternator, it could just be a loose or corroded connection. Just do this with the battery's - cable unhooked or you might weld a tool to your car. Oh speaking of cables are they in good condition?

 

One other thing i would do is remove the stock ground cable to the car body and clean it. I would also install another ground wire cable from the engine block to the negative battery terminal. If you have any aftermarket stereo equipment you must also add another ground wire to the body of the car from the negative battery terminal (you just could do this anyway).
As Tirol says fix that loose connection at alternator.

 

Thanks for the replies, guys! My friend has been a mechanic for a few years and he is the one that replaced my alternator (because you have to take the axle off to get to it & shops wanted $900, which seemed crazy for replacing an alternator). Anyway, something happened with the wire when he replaced the alternator, so he crimped it (sorry, I know nothing about cars, so that's the explanation I have). But, the battery light problem didnt start until 8-12 months after the alternator replacement.

Yesterday, he went in and soldered the wire instead of the crimp because he said he's found the crimps don't last. Maybe I should just get a new wire and go from there? Everyone says she's trying to die and is worn out, but I love this car a ridiculous amount!

 

This is whats wrong with people from today, its all about throwing away what can be fixed for the newest thing, its only a bad connection, nothing to throw the car away for. Also alternators die eventually, its not the end of the world, some are expensive to replace due to the design of the car but still $900 is MUCH cheaper than a new car. Glad you found the problem