Battery light is occasionly coming on intermittently at low speeds. The ScanGuage II battery reading appears to drop to around 11.5 volts or so for an instant and then the reading seems to work its way back to 13.6 volts with acceleration which is the usual reading. There are no codes on my Scanguage II. The mileage is 82K.

I have cleaned the battery terminals on both batteries and the alternator wire. This seemed to help for a few days. I unhooked one battery and left the other one hooked up over night. I checked the voltage in both batteries the next morning with a multimeter. Readings are: unhooked 12.6; hooked up 12.44. Interestlngly, with the batteries hooked up key on, prior to starting, the reading was 11.6 volts on the Scanguage. The batteries are Interstates (Johnson Controls) and were replaced in March, 2011.

Any advice is appreciated. A couple of questions also:

1. Can the local Oreilly's test the alternator for an intermittent issue on the truck?

2. Can the Ford dealer in Harligen, TX test the charging system etc. on the truck? Can they read codes that are in memory for which there is no check engine light. We are on South Padre Island and Harligen is a distance.

3. Do these alternators die incrementally or all at once? Can you drive on a half dead alternator?

4. Does Scanguage II display codes for alternators and bad batteries?

We will be pulling the 5th wheel back to North Texas on December 1 and I don't want to break down on the way out in the boondocks.

Thanks for your thoughts!

 

ScanGauge will display battery voltage. Good indication of what's going on. My alternator died intermittently. It will have to be failing at the time of the test for it show as bad. Glow plugs pull the batteries down when key is first turned on. I would get the batteries load tested at The parts store. Be sure one of the cables (+ or -, either battery) is disconnected during test. A good battery will cover up a bad one if both are connected. I would suspect alt. With the battery's being newer and reliable brand. Best to verify first. If possible, I would get the alt repaired at a specialty shop. Remanufactured units don't have a great batting average no matter where you buy them. Check harness connections at alt closely also. I wouldn't try to limp home because low voltage operation is hard on the FICM ( fuel injection control module). Good luck!

 

Hooked up key on prior to starting the batteries will read lower than 12 volts due to the glow plugs being on. I personally think that you have an alternator getting ready to take a dump based on your pre-emptive trouble shooting and maintenance. They can start intermittant or go all at once. You do need to address this before it takes out your ficm. They hate low voltage.

 

You beat me Rusty. Had to get a fresh beer. LOL

 

Did you clean the 2 main grounds one bt the Power steering gear box and the other one by the A/C pump on the moter block

Your Batterys look good to me 11.6 volts during GP warmup is great

I suspect a bad Alternator

One thing about that battery light on the dash is it seems very accurite everytime mine has turned on something was on its way Out

Look into DC Power lots of folks here run them they are Built very well

https://www.dcpowerinc.com/

I went with the 190amp with the wire upgrade so far so good only been running it for a few months though

 

What a Coimcidence! Me 2 beer. clink mugs lol

 

Hi Bob,
My '04 just started doing the same thing, the intermittent battery light. I checked the alternator output voltage with a DMM, it went from 13.5 cold to only 12.8 once it warmed up. I decided the alternator was bad based on this.
I went to a dealer service to ask about pricing estimate, they told me up to $700 with 3 hours of book labor.

I looked in a Chilton's book about the procedure, it mentions removing the cooling fan and shroud, probably to gain easier access to the serpentine belt tensioner. This sounded like what the dealer would take 3 hours to do.

I looked at the serpentine belt tensioner on the truck, and found there is a little spring loaded pawl that will block the tensioner travel so that the serpentine belt is loose. Just pull on the serpentine belt until the tensioner is at the end of its travel, and use a long screwdriver blade to push the locking pawl into position to block the tensioner travel.

Once I did this, it was a 10 minute job to remove three mounting bolts, remove the wiring harness and pull the old alternator off.

I put a rebuilt unit from Autozone on the truck, $149 for a lifetime warranty. We'll see how it lasts...
Napa wanted $250 for the same thing, and I didn't want to ask what the Ford unit cost.

Don

 

Im with you BUD they charged mme 500.00 for a OEM and it only lasted 1.5years
I had a Ater Market Warrentyy that I thought would cover it is why it ended up at the dealer went to use the warrenty and company was out of bissuness.
That was the breaking point I set out to find out all I could about my truck and thats when I found FTE Great bunck of folks and a ton of info here
At least AutoZone is everywhere if you have an issue just trade it in Just make shure you keep enough tools in the truck to change it at any time they tend to fail alot I dont know why cheap parts and cheap labor to assemble them I guess

 

My truck did this exact same thing. Random drops in voltage. New alternator fixed it.

 

I cleaned all the contacts and the voltage seemed to stay at about 13.6 volts around 55 mph. The battery light still came on occasionally at low speeds and idle. I called Boggus Ford in Harlingen and the service manager said that it sounded like the alternator was going bad and to bring the truck in. I drove from South Padre Island to Harlingen and they got me in right away. The battery light did not come on during the trip.

Within a few minutes, the mechanic diagnosed it. It was putting out 12.6 volts. I don't know if this was at idle or at higher RPM's. They replaced the alternator with a Ford remanufactured alternator. I asked the service agent about replacing it with a brand new one. He said they only replace alternators less than one year old with new ones. I have a Ford ESP plan that covered the cost minus my $100 deductible.

I was in and out of the dealership winthin an hour or so. I see a lot of complaints against dealerships on this forum but I must say tha Boggus Ford certainly treated me well. I would recommend them. Come to think of it, I think all the dealerships I have dealt with on the road have treated me well. And with a 1963 6.0, we have had a lot of opportunities to test this thesis.

What did I learn? Alternators can die incrementally.