Put an Edge CS in my truck back in mid June. Have been seeing an occasional P1378 that only seems to show up KOEO prior to starting. FICM voltage originally seemed locked at 48.0 with an occasional 47.5. The past three weekends I have been seeing 46-48, mostly staying below 48 until the engine has been running 15 min or so. Then it spends most of the time at 48 but seems to be dropping a bit low more of the time.

Today I saw my first 45.5 while hooking up to the TH. Leaving for a 450 mile round trip with the TH in a couple of hours and wondering if I should be concerned at this point.

Appreciate any input.

Thanks,
Brian
2006 F250, 50k miles

 

Might be more of a battery/alt. issue than FICM issue. That's where I'd start first

 

Thanks npccpartsman!

Checked batteries with 100 amp load tester and they looked fine. Is there a better way to load test them? Electrolyte/specific gravity looks good too. Voltage jumps to 13's soon after start. Should I be safe to make my 450 mile towing trip this weekend?

 

For your initial question;
They are electronic and can degrade slowly over time or fry instantly. There is no pat answer to your question. Low voltage seems to be their No. 1 enemy as this increases current which in turn increases heat causing internal component and circuit failure.

 

Thanks 69cj!

Since I'm only seeing a bit of a trend and my efforts have yet to yield an issue, I'm leaning towards making my trip and keeping an eye on the gauges.

How should I go about testing the batteries/alternator? Is my 100 amp load tester adequate? Is there a better/more rigorous way to test ... say something like a software driven 300 amp test or something?

 

I just had Ford install a new half shell FICM and the main cause of the FICM was one of my batteries. But mine was pretty easy to spot as my CTS was showing only 39 volts FICM output voltage. The half shell cost $675.00. This happened on the road while towing my 5th wheel so shopping around for a better deal was not an option.

 

When testing the batteries they have to be fully charged and totally seperated from each other. Your tester may be adequate but a heavy duty commercial electronic unit would be ideal.

 

Thanks for the replies. Decided to take the trip. Will keep an eye on things and evaluate as I go. Wish me luck.

 

I would check the FICM voltages with a VOM right at the FICM to be sure.....AND have your batteries/alternator tested....it's FREE at a battery store. Just be sure to test 'em one at a time.

 

I started watching my FICM voltage earlier this year and saw low 40's after startup, and it would climb to normal after 10 minutes or so of driving. I don't know how long it was performing like that.

At the beginning of this summer it stayed in the low 40's all the time. From that point it went downhill much quicker and within a month or so I saw 17V at startup and 20V running. I had enough of that and had to get a new one before I was stranded out of town. Never had a hard start or running issue.

Chances are you'll be fine, but being electrical, you never know. Good luck!

 

So ... got all set to leave. Started the truck and the Edge did not go above 12.5V. Normally it jumps to 13.1+ shortly after starting. Hooked up the load/charging tester, idled at 1750-2000 a bit, checked it with a Fluke. Edge wouldn't show more than 12.8 or so, spent most of 10 minutes below 12.5V. Load tester showed red for charging system. Fluke measured 13.3 at both batteries;highest value seen during and after high idle. Would drop a tenth or two with lights and AC on, trailer connected. Truck and trailer batteries are fully charged. Truck is still reading 12.8V, 2 hours after shutdown while I have been searching away on batteries/alternators/FICM's. The batteries had been on a tender the past couple of days but were in the 12.7V+ range prior to hooking them up.

I see a lot of posts claiming charging voltages in the mid 13's to 14's. I typically don't see more than 13.2 on the edge but my batteries seem to stay fully charged. Seeing mid 12's concerned me enough to stay home today. Could low running voltage be due to fully charged batteries not driving the alternator to put out higher voltage. Saw a couple of posts where it was stated that a stock alternator would run close to 13V with fully charged batteries. I've seen a downward trend in running voltage, FICM voltage and been getting an occasional P1378/FICM logic voltage. Maybe just chasing my tail but I don't trust it for a long trip right now.

 

If it's any consolation I run 12.7 to 13.9 depnding on what the batteries need. I pull a 31 ft. 5er and all seems well. Had the dealer check it out 2 years ago and they said all is good. Voltages are still the same. You do need to wait for the gp's to shut off. This is with a stock alt. People with a DC may get diff. readings.

 

Thanks for that last post 69cj. The voltages you posted led me to give my trip a try. My voltages stayed in the mid 12's for the first half an hour or so then went back to the low 13's that I'm used to seeing. 9 hours pulling the TH including several long steep grades and 100*+ OAT's and everything worked fine.

 

Glad to hear it. One of the reasons I'm told that Ford dummied up the gauges is because some people would be back at the dealer for every slightest change in readings. I don't agree with that methodology but it is what it is.

 

Not sure what your readings are but for 225.00 and some change you can have peace of mind that your not gonna be stranded on the side of the road,or fry the FICM.Two new motorcraft batteries will take the worry out of this situation.Ive been working on aircraft for nearly 30 years,we have time change requirements on certain parts.I just changed out my batties for this very reason.2006 F250 CC 4x4.The first break down on the road will go thru that 225.00 pretty quick.
Good luck.