I understand what you're saying.

Signaled to shut down but erratically. My understanding of what the BMS is supposed to do when the battery has reached 80% charge is to taper down the voltage to reduce torque resistance from the alternator but still charging at a trickle voltage. That would be signaling coming from the BMS. Certainly not what it's doing and what was seen is not normal.

I pulled the sensor plug in and out several times to improve the connection by your reccomendation to re seat. Then I connected my CTEK charger to bring it back up the state of charge it had. The SOC when the truck was in sleep mode dropped to 12.52. It use to be 12.67 and remained that high throughout the summer. That is a symptom.

Troubleshooting:

My plan right now is to see if it happens again while driving. If the voltage drops like I saw today I will open the hood and take a voltage reading to see if it's true to ensure that the engineering mode display isn't causing the erratic display of voltage. Likely it's not.

Second step will be unplugging the sensor to see if the voltage remains at 14.6. We know what happens when you pull the sensor plug, the battery gets a never ending full charge of 14.6 volts. The purpose of this check is to determine if the alternator is causing the erratic voltages on its own. We'll see.

The voltage staying at 14.6 yesterday was like the BMS sensor being disconnected. That leaves the plug in question for maybe it was but it's just an observation at this point. Nothing yet conclusive or eliminated.

 

Bluegrass, re seating the sensor plug may have been the ticket. CTEK completed charging.

The drive today was identical. Voltage to the battery remained above 14 the whole way with one observation.

At the beginning voltage flickered between 14.7 and 14.8.

After stopping at Burger King like before, the voltage came down and flickered between 14.5 to 14.6 then 14.4 and 14.5.

Normal? What do you think? Shall I unplug the sensor just to see if there's any observable difference?

 

I would just go with it and see. If it returns, then it proves that was not the cause.
Today while waiting for the misses to finish composing a poster on a publishing program for a music group and send it via e-mail, I was looking at my system again. I have to back her up in case she has an issue to solve.
Every time I look, I see things more clearly just using a SCANNER.
This time the system voltage in Eng Mode said 14.2 after cranking.
My scanner read it out as 14.241 volts to three place accuracy the dash mode does only one place to the right of decimal point, at the same time. The tipoff is the dash digit flashes due to small variation in rounding up or down that cannot be seen as more than a flashing.
And sure enough, the Scanner showed the cranking voltage momentarily during a re-start, just to see if it could be seen same as on the Dash.
.
As to your higher voltage readings, whether your program is set higher or your frequency of charging is doing it, don't know.
I don't do charging unless there is an issue since I can see it off the Dash display.
Last time I had to do it was due to leaving the parking lights on all night.
There is no auto system turn-off for that in cases where the vehicle has to be left in a danger situation unattended or stranded.
The only auto turn-off is a dead battery in that case. There are a lot of lamps involved between front and rear if you count them both sides.
I did not notice the chime was sounding when I got out with the key in my hand. Paid for it the next morning.
Later.

 

Yea, I'll just monitor it for a while, look at some ground conditions.

Thanks

 

So far so good. Voltage remains at 14.7. Re seating the sensor was likely the fix.

As for entering Engineering Mode, there was about 5 attempts where I couldn't get in. Later I discovered that I was holding in the OK button too long. Engineering Mode would popup on the screen for a moment and then go back to the regular screen. When that happens, you have to key off to try again.

What you have to do is, release the OK button right away as soon as you see the mode pop up on the screen and it will stay up.

Another thing. There are many pages to toggle through with clicking the up or down button. To reach battery voltage, it takes 42 page down clicks to reach it. 2 clicks up from battery voltage gives you trans temp and 6 clicks up from battery gives you coolant temp.

Most of what gets displayed in the 60 some pages is not obvious or immediately understood. There must be a reference somewhere to it all.

 

Look at the titles of many.
It is giving info in Hexadecimal to be converted to Decimal values. Some reflect dash mechanical values in Hex, Degrees Celsius etc.
As you see some are ports and some are hardware and software values and versions.
One that is of value when there are parts of the system that are or have been set with code, that is still set but does not show otherwise. Those are not PCM codes but other body code indicators. It should read Zero in a clean system.
Bottom line is the Dash Eng Mode displays info in a mixed presentation format.
It has been this way since about 2001 when the dash display became nearly fully digital driven getting inputs from the PCM and some Sensors to a Dash microprocessor that drives the Gauge movements to fixed positions on some. In these older systems the readout was in Octal numbers from Zero to 255 and some in Decimal. For example, Octal 255 = full fuel tank etc. Other values = 1/2, empty etc. I have all that info from years ago. That system even shows code for the old PATS system faults.
.
Today, these vehicles are full blown Computer controlled with peripheral modules controlled over Buses with ID, two-way data flow and separate diagnostics with their own code. This system can be communicated with through the DTC port with a Tool that can send commands and see the result, for testing.
This type of system was my work for most of 20 years begriming in1980 before the advent of other common systems. Get this, the Processors were huge and used 64-bit words, two of everything, auto switchover without missing a beat. The systems worked 24/,7 365 and worked on live when a fault occurred.
Ony thing that permitted it was each peripheral frames had 2 local controllers such that one could be taken offline to work on, powered down etc. Then tested from a Terminal with Screen and Printer paper output that had to be analyzed bit by bit in the word positions. There were no easy codes to point to anything except the frame in trouble and large circuit drawings in combinations of block and schematic form linked to other pages by notations.
You see how easy it is for me to relate to the truck system without havening any official Documents.
I'm not always right but pretty close.

 

Some of the titles you've pointed out I recall seeing but with figures that have no meaning for me of course.

I've really haven't taken the time to just sit in my truck with the engine off and go through all the titles to see what can recognize that would have any practical benefit. Observing battery voltage is certainly practical, especially for the OP looking for answers to a problem but also anyone who reads this thread. Water temperature as well, at least for me since I don't have a trim level that displays it on screen. Trans temp I have in the menu. I also recall other titles with understandable data I have already available in the dash menu.

You have posted many times your advice to venture into the engineering mode. I don't know who's heading your advice but as always your response to anything has always been complete and informative. I would have never known about the erratic voltages taking place from the alternator. Thanks for introducing it. I believe you're the only one who has, as far as I know.

 

Just getting back. Building a house and have been tied up. The situation with the unpredictable starting has gone from bad to worse. I made an appointment with the local dealer at the end of August and their earliest open date was October 31st. They had the truck for three days before they called to tell me they had solved the problem. Per the dealerships "Head " mechanic the problem was the engine was low on oil. So they had changed the oil, updated the computer, put in a new dip stick and charged me $400..
You might be surprised to know that it did not fix the problem. The unpredictable starting continued until I ended up in a service station and the truck would not start at all. I called for a tow. The tow guy tried to start the truck with a jump start, no go. We loaded the truck on the rollback and took it to me house about five miles away. We unloaded the truck and I tried to start it. The truck started like brand new.
The common symptom seems to be that the engine is hot. It starts fine in the morning. Drive 5 miles, it might hesitate on the start. Drive 20 miles, get the engine good an hot, and it won't start until the engine cools down. The truck is back in the shop and the latest news is there maybe a problem with the engine. I can't wait to hear what this is about.
All advice and help is appreciated.

 

I would demand a refund on any work that was done previously that didn't fix the problem less the oil change.

 

From the thread below, after running hard and then stopping for a few minutes the starter gets heat soaked and draws excessive amps to turn over. Problem gets resolved after letting it cool down.

Start at post #14...
https://www.f150forum.com/f12/2018-f...unning-496138/