On my third alternator in 2 years. First lasted 100,000 miles, second about 25,000. Third has around 7,000 on it. Alternator change based on battery light coming on and confirmed with voltmeter with engine running.

Each time, battery light would come on intermittently after start followed in a few days by staying on steady. Both replacements have been NAPA lifetime units so no money involved.

The battery light has been intermittent now for a few months and I'm unable to run it down. Voltmeter verifies a noncharge condition with the light on, then a jump to around 14.4 when the alt kicks on. Light can come on anytime, day/night heavy/light load, stay on a few secs or several minutes.

I've read about the heavy draw the glo plugs exert when they're doing their thing, and the fact that even when the glo light is out that they can still be operating. Is it possible that they are cycling at odd times drawing my voltage down? I've also read about a pigtail on the alt but haven't found one on mine.

This is getting to be a prob as my wife won't drive anything that's ing up and I'm running out of vehicles for her to drive...

 

It's probably the regulator/brush holder assy. My daughter's escape did the same thing and it was from the slip ring wearing the brushes down to the point they wouldn't make good contact. It's just a motorcraft thing I guess. Her escape is on it's 3rd alternator that I've replaced in about 55K miles. The last one didn't last 30K miles and it has my old superduty alternator on it now.

FWIW--the alternator repair shop here says that if it wasn't for repairing motorcraft alternators they wouldn't have gotten through the recession. They average about 2 a day.

The alternator won't charge with the glow plugs on but it shouldn't turn on the battery light either. That's controlled by the hybrid electical cluster in the dash. Like I say...it's probably one of the brushes not contacting the slip ring all the time. Just get NAPA to replace it. Also.......I'm doing a little research. If you don't mind, with the truck running and battery light off would you check at the battery for AC voltage. Red lead on the positive black lead on the negative. Just curious.

 

Welcome to FTE flyday58 Make sure you check out the Tech Folder located at the top of this forum.

Going to give you my Honest opinion here. Electrical problems are just that and harder to diagnose without seeing the vehicle. Grab your volt meter, make sure all batteries and running voltage are in spec with good clean grounds.

Napa, Autozone, Murphs or Joes clean parts around the corner sell low quality to satisfy your wallet. Napa, when I deal with my local one, has different grade or rated parts.

Report back on what you see

 

Will get back to you on that.

I'll check with NAPA. It's a $350 lifetime-warranty unit and supposed to be the best they got. Maybe it's a Motorcraft disguised as an after-market unit. Hmmm...

 

Out of town till the 22nd, will check the voltage when I get home. Had to drive to Mobile this a.m., 65 miles worth. Battery light was out until crossing the Bama state line, about 35 miles. Came and went a few seconds at a time before coming on for good for the next 20 miles. Running 75 on the interstate with the light on. After getting off the interstate and heading thru town, light went out and didn't come back on all the way to the aero puerto. So I'm wondering if indeed the brushes are floating at the highway speeds but do better with stop n go stuff. It just don't matter cos I'm changing it when I get home...

 

[ It just don't matter cos I'm changing it when I get home...[/QUOTE]

Maybe not. Started truck this a.m. and pulled out of the drive to get the light to come on, which it did as soon as I exceeded about 15 mph. Pulled back in, popped the hood and checked the voltage. I've got 14.15V at both batts and 14.26V at the alternator. Light is on the entire time. Tried wiggling all the wire bundles I could reach and particularly the plug going into the alt. No change. I read a post that said some people have found the wire chaffed that will set the light and that that wire only turns the light on and off. Will keep looking.

 

Before you hose "Motorcraft" be sure you are actually putting the right Part Number on the thing, and the part is not a "fake" or "workalike" that the parts counter guy hands you.

Since the alternators all "fit alike" and to an untrained eye who do not disassemble the device to check, they look the same, there is enormous temptation (not to say there are not honest people out there) to hand you a equal or better "rated output" alternator, and either charge you the lesser price (or sometimes, if they are dishonest, the real Part Number price).

The real McCoy Ford Alternator on mine lasted over 230,000 miles, and finally died because the bearings wore out, not the electrical components.

The NAPA part lasted about a year of light use (I did not put it on), and was promptly replaced with a custom part that I speced out.

It is rated for a piddly 145A --- but it can put close to that out all day, all night, and at close to 100% duty cycle, right up to 100F ambient temperature (and fierce underhood temperatures).





Assuming you are a stock vehicle with no unusual electrical loads:

A) The stock motorcraft alternator is a specially ruggerdized unit that is designed for a much higher duty cycle than many (light vehicle) alternators.

That part is not generally known to parts guys who see the part number as different, but the looks, shape, etc. is the same.

People look at the low amp rating (e.g. 110amp) and sneer at it not realizing that it can put out close to 100amp all day --- while a higher rated one might only put out their "higher" rating briefly.


B) NAPA etc. give you a "fit alike" that have a duty cycle that is way below the factory one --- that is why they crap out

C) No one I know of in the auto-electric space generally advertise their alternator "design / maximum" duty cycles.

They give an "amp rating" which is a bit of a sick joke on people who don't know better.

e.g. you can have a 200amp alternator with a 2% duty cycle, and an RMS (Root Mean Square) duty cycle of maybe 60 amps at 100% duty cycle.



Another way to look at this:

Your starter is rated around 3kw.

That is, 3,000 watt.

But it can only be used very intermittently --- a duty cycle of around 1%.


Your options:

1) Get a trusted Ford parts guy, and get the real McCoy Ford alternator (not cheap) and NOT a clone they can flog on you.

2) Get a real high duty cycle Alternator (not cheap).


More and more, I am noticing that Ford is not telling people up front that their parts are simply... better... and let customers who buy aftermarket find out the hard way.

 

ANYWAY, the alternator appears to have good output now while the light has become a nuisance. Anyone ever found a good fix for this?

 

Check for a bad pigtail.

 

Hey gearloose, In his first post he said he couldn't find it.

To the OP: If the end of the pig you're looking at has teeth, try looking at the other end for the tail.

Merry Christmas 6.0 fellers!!

 

Maybe he can haul something beside.... LOL




Look for this:

http://www.repairconnector.com/produ...k-Housing.html

 

Just don't sprechen-zie the lingalie. From the link I quickly surmise the pigtail is the plug that goes in the alternator. Mine has two wires, and both look fine at the pigtail end. Still could be rubbing somewhere else in the harness. Will keep looking.

 

You cannot tell a failed pigtail just from a visual inspection, unless you have x-ray eyes.

It can even test OK with an ohm / continuity tester and then crap out.

If in doubt, replace.

 

I have the exact same problem with my 6.0, its been driving me nuts for the past 9 months. Everything tests OK, and I can never pin point the problem myself. Ford also said it was probably the regulator, and they were more than happy to fix it for me for major coin$$$$.

BTW, this all happened immeaditely after they replaced my FICM for major coin$$$.

 

FICM failures are exacerbated by weak / bad charging / battery / wiring / electrical systems.

Hence, if there is a FICM fault, you almost have to check out the "supply" to see if that is a contributing cause.