Battery light started to flicker this morning. The owners manual says that the battery may not be charging correctly.

Is this the battery itself not holding a charge and should it be replaced? It is about 6 yrs old. Sears "Gold" if that means anything.

-or-

Is it the alternator? How do I tell if the alternator is charging properly and if it needs to be replaced?

As always, any help is always greatly appreciated...Scott

 

You mean the red idiot light that says "AMP" inside the battery symbol?

It means frankly, low amperage in the system. A 6 year old battery is due for replacement anyway. Could be the battery, but more likely the alternator. If the light is "flickering" it means that the alt is putting out energy, but not what it should. Does it get steady if you use accessories(power window/seat, lights, ect)?

With the key and motor off, get a multimeter and test the battery. If it's less than 11.5 volts, replace it pronto. Normal is around 12.6 or so. Now start the engine, and wait about 30 seconds. Test it again. Now should read around 14.5 volts, but not more than 15. If it's in the 13 range, the alt is going. If the battery is still reading it's normal(w/o motor) voltage or only slightly more, the alternator is bad.

One final test is to get your baseline reading for the voltage with motor running. Then have a helper switch on the headlights, while you watch the multimeter. The voltage should drop a bit, and return to it's previous reading within a second or two. If it drops substantially, or doesn't recover, you're not charging properly.

First, replace the battery. It should be replaced anyway even if it tests fine, the lead plates are getting brittle or could already be cracked. See if that helps. If not, then you're going to have to replace the alternator.

EDIT: If you have the 95 amp alternator( I think you do unless you have the towing package, then it's a 130 amp) and options like power windows/seats, the truck is close to maxing out the alternator AS IS. You have very limited room for add ons. If you have a powerful stereo and electric fans, you could have been overloading the system for a while. The alt will keep up. For a time. Overloading it WILL cause the alt to fail prematurely.

 

alternator brushes are worn and need replacing.

 

I agree. You need to fix or replace your alternator. But to test it, crank your truck, turn on the lights, and then shut your truck off. If the lights get dim, then your alternator is working to some degree. But like someone said earlier, that idiot light measures system voltage. If your engine is running then the voltage should be over 13-13.5 volts at least. Oh, and when you replace your alternator, get the highest capacity one you can. It will give you less trouble in the long run, and help you jump off cars, etc.

 

Here's what I found after testing.

Engine off: Battery is about 12.0 - 12.5 volts.

Engine on: Still get 12 - 12.5 across the battery terminals. No increased voltage noted. Only a very slight dip in voltage when lights, radio, etc is turned on.

I have noticed that the windows have gradually been moving a bit slower these past few months.

Battery light still showing solid with no flickering at startup or driving.

Looks like I'll be swapping out an alternator soon. I'll go with the 130 amp.

Thanks for all your help...Scott

 

Yep, your alt is shot. Either get it rebuilt, or better yet, just replace it with the 130 like you said. You get a lot more juice to play with for add-ons. Since you said there was no increased voltage(but didn't drop) the alt probably is producing power, but just enough to keep the motor running. If it wasn't working at all, the voltage would have dropped with the motor running.

Even though the battery voltage is okay, I'd still replace it. Typical batteries are rated for between 3-4 years. More than that and you're borrowing time. Volts isn't a good measure of if a battery is "good" or not, you need a load tester. Most auto stores will do this for free. You might get lucky like I did and have the kid behind the counter drop my battery, so I got a brand new one for free. Cool.