Follow up in case anyone else gets this issue. There was a code produced, I'll have to pull my paperwork to identify which one. As the tech went thru the process via Ford's Workshop Manual, he tested all components, batteries, alternator and connectors. The first suspect was a connection seeing as how the problem occurred after a period of continuous rain and fog, The message was still there. Made several trips to Northern Wisconsin and back with the "service charging system now" message flashing off and on. about 1/3 of time displayed along with the Battery light. Even with the light on the system was putting 14 volts out. Tho disconcerting it was sill charging the battery.

Further into the process it was discovered that the Primary Alternator was all over the place in producing proper voltage. The secondary was normal. This was spooking the PCM , as it should, even though the system was still operating as it should. Replaced primary alternator with a new one.

No change - Service message light came on and stayed on. Noticed headlights flickering against wall and no change when increasing engine RPM. Batteries completely discharged next day and had to charge overnite to move vehicle to dealership. Tech and I discussed new events. Upon further review, it was determined that the replacement alternator was bad also. Ordered another and 2 days later it was installed and so far so good. Fingers crossed - drove vehicle hours with no messages.

Thought I would post as no one was able to add any info. For the record, I am a service writer for a small ford dealership with 3 diesel master techs. This was a new issue for them to diagnose on a 019 6.7 with such low mileage

 

Glad you found the problem. Could you help me understand why the Secondary Alternator did not pick up the load when the Primary failed?

 

It's not that the load wasn't picked up but the result of the PCM knowing there was a fault with the Primary Alt. Add to that there is a PCM function as to how/when the Secondary Alt is utilized. I'd bet part of that requires the Primary to be functioning properly.

 

I am having this same issue of the charging system service soon light coming and going. I only get the warning when I am towing my TT. I have replaced the camper battery, and relay 37. still have issue. I have since cleaned the trailer and truck connections with electrical cleaner. Just trying to diagnose this myself as the stealership wants $150 to diagnose.

 

Can anyone tell me if I am supposed to have a fuse in slot 27, or because I have factory installed TBC, i only need a relay in 37?

thanks

 

I got the same problem. Any updates? Dealer can't fix it. 5th time in, it is ok for for about an hour after I get it back from them and the warning light goes off again. 2017 Lariat Ultimate F250. They have replaced the primary alternator twice so far, also some pigtail connector on the 3rd time in to the dealer.

 

Oh Skillethead I feel for you. I started to get the warning and light a couple of days ago, without pulling my camper. Talked to the stealership where I bought the truck they can't get me in at all because they had three techs quit. Got an appointment at another stealership on July 16th!!!!! In the mean time since my warrenty is over I have a local diesel mechanic i am going to talk to when he comes back off vacation. More to come.

 

Mine has been in the dealership all week, no idea when I will get it back. I will let you know what happens. I sent you a private message with my contact info.

 

FYI, with only 2 posts you cannot send a PM. Your message is posted on his profile page. You or he may want to delete your personal info.
@ae6940t

 

Some info uploaded below.

 

Good to see you back around @Gadgetguru.

 

Thanks for the great info!! Hopefully the tech at the dealership will follow this and figure it out. Thanks again!!

 

so update here, I had my truck at the local guy he could not get it to fault (for lack of a better term). Looks like I'm off to the stealership.

 

Hope it's an easy fix. My dealership(long lewis ford in Muscle Shoals) has had my truck for going on the 3 weeks.

 

Well the following week i am heading to Kerr Lake in NC, with my truck and trailer in tow, also the first post i noticed the picture is outlined in yellow, mine is Red. What color is yours?

 

I was having a lot of electrical issues with my truck, the Ford dealership replaced the wiring harness' under the cab that had water intrusion. There was an update for certain 2017 models. The only thing that did not go away was the Charging System fault. It would act up more with rain or while pulling a trailer. I cleaned the plugs and found some moisture in the wire harness plug to the trailer adapter at the bumper. It has been sunny and hot lately so I unplugged the wire harness from the trailer plug at the bumper 2 days ago and I have not had the Charging system light come on since. I don't know if it is the wire harness or the plug yet and don't know for sure this is where the problem is since it has only been 2 days but i will give it a couple more before I go replacing parts. You might try running a couple of days with the harness unplugged at the bumper and see if it makes a difference.

 

Tinman here. R we talking 2019 or 2017?? Original post is “2019”! Thanks

 

Similar issue, had “Charging System Service Now” message appear. Took it to dealership and this was the response/fix.

AVR BATTERY/ALTERNATOR/STARTER CHECK.
CHARGING SYSTEM LIGHT IS ON.
verified customer concern, charging light on, scanned for codes, retrieved p0625 generator field/ f terminal circuit low, wsm 411-00 charging code, diag and testing, ppt f f1 no, tz yes, t3 yes, f4 no, measured volt at 6.25 volts, when putting a load to test, voltage disappeared, circult s0098 ye-rd was measured with 10 million ohms, c102a to c1046 had an open, over laid wire after customer approval, cleared codes, working properly

over laid wire after customer approval, cleared codes, working properly after connector 102c with battery voltage

Essentially they found a broken connection/wire and put a new one in. Seems to be work now so just posting this in case it helps someone else out.

2018 F350 6.7l