Im experiencing a flickering battery light. Since it has gotten cold I have noticed it. The truck starts fine and runs fine, just dont know why the lights coming and going. Both the indicators in the top are green and the connections a tight. Does it neeed water added? From my old Dodge truck when the battery light was on that meant it was about dead, but this truck starts no problem. Thanks for any help.

 

A flickering battery light sounds like the alternator has dropped a diode or two and is not turning out quite enough voltage to make the system happy. Probably enough to keep the battery reasonably well charged (maybe 70% of capacity) but not high enough to be normal.

Break out your voltmeter and check voltage across the battery with the engine on and off. You should see ~12V with the engine off and 13.5-14.5 with the engine on. If you're not seeing 13.5 or better with the engine running, replace the alternator.

 

Thanks tvsjr I went out and checked both batteries and they were reading between 14 and 15 while running. Our volt meter has a needle so it floats around a bit. I looked in the water resevoirs and it seems low to me but not sure what level is good. Is it distilled water? Also my pos. terminal on the drivers side has some corrosion on it could this be the answer? Thanks for the time I want to check all this stuff out before I have to buy a probably very expensive alternator.

 

My 03 was doing this. The light blinking on and off. I replaced the alternator and it has stopped. It has not blinked since I changed it. Ordered it from the dealer and changed it myself. yes expensive.

 

A needle that twitches around a lot might well be warning you about a bad diode...

It should be relatively calm, especially with those two big Group 65 batteries there to dampen out the fluctuations.

 

Yup... Brett's right. You shouldn't be seeing fluctuation on your voltmeter... actually, such fluctuation is why I keep my old Simpson around. Sometimes, an analog meter will tell you a lot more about a situation than a typical digital meter.

Go ahead and fill the batteries up. It is, indeed, distilled water - make sure you don't get any contaminants down in the ports. Beware, the little green ball will go away and you'll see the red one. That's simply because the water (with a different specific gravity than the acid) is on top and doesn't mix fully. After some driving (and shaking around), the green ball will likely return.

Also, yes, clean up your battery terminals. Get some good cleaner and protector (I use a cleaning formula in a yellow can, about 12oz., that is dispensed as a foam and turns pink in the presence of acid) along with a good wire brush and a terminal brush. Clean everything up, apply the red/green discs underneath the terminals, let everything dry, then coat it (twice, usually) with the spray-paint-like protectant.

Essentially, work through the little stuff. However, I'm betting that it is, indeed, a dying alternator. Depending on the failure mode, a dying alternator will do strange things. We had one on a 2003 F-150 SuperCrew that would load-test properly, produce "acceptable" (but slightly low) voltage, etc. However, thanks to the dead diode, it was generating an AC component on the DC output. This manifested as a nasty hum in transmitted audio in the commercial radio equipment installed in the truck. It took some convincing to get Ford to swap it out... even worse, it took three tries to find an alternator that wasn't bad from the factory.

Good luck.

 

Thanks for all the advice everyone. Il give everything a try and see what happens!

 

Well I cleaned the battery and filled the water and the light still flickers! Oh well time for a new alternator. Do you guys have any tips or tricks for installation? A short how to would be awesome since im still a newbie! I cant believe Its going out this fast , my 92 jeep wrangler that ive had for about 7 years has the original alternator and its been crammed with mud and water most of the time and its got 160k miles on it , still works fine. Thanks for any info.

 

Ford's produced quite a few less-than-decent alternators over the years. I went through four alternators on a brand-new 2003 F-150 SuperCrew trying to find one that wasn't bad (dumping an AC component on the DC rail) before finally getting one.

I've never had to replace an alternator on a 6.0, but I understand it's not the easiest task in the world. Try searching the forums - I know it's been discussed in the past.

 

Since I have now replaced my alternator three times in the last 2 months, I have learned that it is quite easy to accomplish.

Using a flashlight, shine it down on the idler pulley. You will see a bright, shiny spring loaded metal "finger" poking up in your direction. You can reach it with your right hand very easily and pivot it towards the driver's side (clockwise). This is a lever that will hold the idler pulley in a "locked open" position, allowing quick changes of the alternator and belt (okay, not so quick on the belt)

To perform a quick alt. change follow these steps:

1. Disconnect both negative battery terminals

2. Place step stool or elevating device on passenger side of truck if you are short like me (5'-9")

3. Grap belt with your left hand, positioning the AC hose on top of your wrist, and place a finger of your right hand on the idler "lever"

4. Pull the belt with your left hand towards the fender and pivot the lever to hold the idler pulley open, which will keep the tension off the belt while you replace the alternator.

5. Disconnect the electrical connections & three bolts holding the alt. in place

6. Remove old & install new alternator. Hook up all electrical connestions, including the batteries.

7. Grab the belt and pull up briefly. The spring loaded lever will pop back into place. Make sure before you do this to check that the belt is installed over the alternator pulley and straight on all other pulleys. You are done.

The whole process should take about 10 minutes.