Hi,
my name is mario, i am from vienna/austria. My truck is a 2004 F350 6.0. These trucks are not very common in Austria, so nobody knows how the work really...
Have a problem with my charging system with dual alternators. When I cold start the truck, after around 30sec the battery warning light comes on, stays for 30sec to 1 min and turns off. Just when cold start the truck, when engine is warm, no problem.
Already changed the lower alternator because I had some volts when I did a voltage drop test on the ground side.
Problems started with a mouse or something like this living in the area of my turbo und are some of the isolation on the top wall of the turbo. From then the battery light came on. Then FICM died, reason was a short to ground on the main board. So I had to change the FICM. Battery light stayed on. Did a drop test on the alternators and found volts on the ground side of the lower alternator, changed it. Problems still there.
I am scared the I kill my FICM again...
Any ideas?
Thanks for your help

 

I've not had the pleasure of working on a dual alternator system, but it sounds like you have an interrupted control wire possibly to the top primary alternator. The dual alternator system turns on the alternators separately through the PCM during the cold start phase when the glow plugs are heating to prevent an over-voltage situation to the glow plugs. It's going to be a situation of tracking the operation of the two control circuits to the alternator, then tracking the interruption, and finally splicing the wire back together. Unlike the single alternator trucks where the alternator turns on is controlled through the cluster only, both of these start at the cluster for turn on, but the control then goes through the PCM. Since you sometimes don't have the battery light on, everything is fine until after the PCM.

I'd post the two diagrams for initial review, but I've included them at the end in the Ford Service Manual diagnostic procedure which should walk you through the testing phase of both alternators. But it sounds like one is working. The circuits are very simple. All wires are color coded at the insulator. The I circuit turns the alternator on, the A circuit is the sensing circuit, telling the alternator(s) how much they need to charge, but it sounds like an I circuit issue.

Primary Alternator


Secondary Alternator

 

Thanks for your assistance! Will check everything out and will report

 

One more thing, I have a livewire on and when I start the engine the voltage dropped nearly 10volts as long glow plugs are on...that's not the way it should be, or?

 

It shouldn't be that low. It is because you are running on battery power only at that point, and you are in the range of having the FICM fail.

If you have a 110a alternator up top, this is what it should look like, around 12v. The lower right side of the chart indicates Ford's warning for impending FICM damage.

 

Where do I get such detailed instruction like you posted? Is that from a workshop manual? Where can I find something like this?

 

You might want to charge and load test those batteries also.

 

Good point Mark.

AP, that's from the official Service Manual for the truck. You can often find the DVDs on eBay.

The generic brands I find are often lacking.

 

Okay, when I bought the truck the dealer put new batteries inside and I went on a roadtrip with the truck. 3weeks, 6000km and it had minimum 30°C all the time. When I came back the truck was sitting a while and I used it again when it got cold and the problem started. Maybe it's just that the batteries are to weak when it's cold to cause the problem and when it gets warm everything is okay...I check my batteries how much CCA they have, maybe the dealer had put to low inside...that can cause the problem also, right?
Minimum 800CCA is good?

 

The trucks came with 750CCA so 800CC would be fine.

The batteries will not cause a battery light issue, only the alternators.

 

But bad batteries can give alternators fits (and eventually damage them)!

 

No argument with that.

 

Wow this is old stuff, I thought we had this sorted out years ago... FICMs and dual alts? I fixed the FICM myself using higher higher Bdv, low sat V and high gain MOSFETs and better quality capacitors. During my testing my modified FICM inverter board put out full power (48V out) down to 10V in without ill effect. With OEM battery cables and initially clean ground connections the cranking voltage wasn't any lower then about 11.75 VDC.

My OEM dual alt started acting up as described but I have ignored it for the last 1 -1/2 years as the light would go out with revving up the engine or tuning on the head lights and has kept the Northstar batteries fully charged! Note after the first five years with OEM Autolite battery's they were replace with 2 Northstar AGM group 65 (1050CCA) which have done well for the remaining 7 years to date (even when the temps reached real temp of (-35 F).. Haven't really looked into the light issue since it would go out eventually and kept the batteries charged, I dismissed it as a corroded ground connection(s). I know there are those of you that have written extensive papers on battery cable size(s) and balancing battery load/charge but these points seem moot as long as the system operates reliably and batteries are charged?

14 years and 185K of light towing miles later mostly on original factory OEM parts, my only concern now, is whether my current problem is an leaking EGR cooler or head gasket !!

 

Certainly a battery with a shorted cell will cause the alt to run Hot and thereby cooking the battery, it becomes a matter of which will give up first!

 

Funny, slowly the hole picture gets brighter and brighter. Before I bought the truck, on a two day test-drive, I had problems with starting the truck so I brought it back to the dealer. He found out that there was a shorted cell in the main battery and there was also a bit of noise from the alternator area..like I found out now, the dealer put to weak batteries inside. Just 650CCA, and I drove like this two years. When winter started last year the problem with the battery warning light started, maybe the alternator was already damaged, quiet sure because of the to weak batteries and the cold weather the light started to illuminate, I ignored it...a bit later FICM died, to low volts when cold (under 10volts)...bought new ones yesterday with 1000CCA...battery light still there...looks like the top alternator voltage regulator is dead. Will change the top alternator