Alternator issue?

[filteredsoul]

Hi everyone,
First of all, a big thank you to all who have helped me with my various troubleshooting issues over the past few years! You have saved my wife and I TONS of money.
We own a 2004 Ex XLT with the 4.0 V6. It's got the funky transmission, but thanks to you I've replaced the rear wheel bearings, sway bar links/bushings and replaced the blend door actuator. That's a ton of money saved right there! My latest issue seems to be electrical. My wife was driving to work the other day and noticed that the battery light came on when she pulled out of our subdivision. It's kind of a blind corner so she got on the gas a little harder than normal. She thought the battery might be loose because of turning the corner hard. When I checked it, all was good. The next test was to point it straight and nail it. Sure enough, at around 4k the battery light came on (and stayed on as the rpm's increased) Below 4k everything seems fine. I read all the posts about battery lights flashing and it seems the alternator may be the culprit. Possibly the regulator not being able to regulate the higher voltage? I took it to Advanced auto for them to check and everything checked out ok... but they didn't have the ability to check the amperage. NAPA didn't either so I may call around to see if there are any shops that can.
To throw in another variable, I just got the oil changed today and they said the serpentine belt was getting to the end of it's life. It's the OEM belt with 106k miles on it. Visually it looks ok, but they're probably right. Wondering if a worn belt could be adding to the problem?
I'm still thinking it's the alternator... any other ideas or ways for me to check anything else?

As always, THANK YOU in advance!

Dan

 

[Exproblems]

Wondering if a worn belt could be adding to the problem?
I'm still thinking it's the alternator... any other ideas or ways for me to check anything else?

As always, THANK YOU in advance!

Dan

My advice, change the serpentine belt first, it's the cheapest fix and your current belt (106K) is way over due for a change anyhow. Next, get the battery tested besides the alternator amperage and go from there.

 

[filteredsoul]

Thanks for the advice. I know the belt needs to be replaced also. As far as the battery, both the oil change place and Advanced checked it and it's fine. In fact, the strip I got from Advanced shows everything (battery and charging system) as checking out just fine. I guess the little portable electronic box with the pos/neg battery leads was able to check everything except the alternator amperage...
With no load, the battery was at 12.4v with a load it read 13.95v (this was with the high beams on and the blower fan at full speed.) Unfortunately my '04 has the fly by wire throttle so the car wouldn't rev past 3.5k in their parking lot...
Also, I tried looking at my volt meter (on the dash) as the battery light went blinky, but it didn't budge. It stays in the middle at any rpm.

 

[Foo392]

The alternator is really simple to remove, take it out and bring it to your local parts store and they'll test it for free.

 

[Exproblems]

. As far as the battery, both the oil change place and Advanced checked it and it's fine. In fact, the strip I got from Advanced shows everything (battery and charging system) as checking out just fine.

Well if you have a totally bad alternator, your battery will eventually go dead from lack of re-charging by the bad alternator and you will be driving(electrical system) on battery power only till it runs out of power. From a recent post that had a similar issue as yours, the persons alternator went totally bad, but their battery was still good, their vehicle went into "limp home mode" because the battery power only could not handle the electrical system draw of energy. Once they replaced the alternator, their problem was solved. I would also check for shorts in any wiring (starter wiring included) in case the problem with the electrical system is there. You could just buy a new or remanufactured alternator and install it and see if the charging system light goes out. If it doesn't fix the problem in a day or so, return it to the parts store for a refund. Just don't tell the parts store you installed and used it, just tell them your problem turned out to be something else. Since you have an Advance Auto Parts store near you, you can save $40 off the price of the alternator by using an online coupon code from www.couponcabin.com. The price of a new alternator is probably over $100 so the $40 off coupon on an order of $100 or more can be used. Just use the coupon code from www.couponcabin.com when you order the alternator online at Advance Auto Parts.com and select to pick it up at a store near you. Use a different store for pickup than the one you had test the battery charging system.