I have a 2016 F-15XL with a 2.7 liter engine. I was driving tonight and the cruise control stopped working, followed by the battery light coming on. I pulled over, shut off the engine, took a quick check under the hood and found nothing wrong. So I turned around and decided to race the 30 miles home, or see how far I could get on the battery before it died.

ABS and traction control turned off and the power steering became stiff. Then the display indicated lights dimming then a few minutes later the headlights turned off, at 8pm. I got a tow home. I think it was about 10-15 minutes from battery light on until the headlights shut off.

I suppose the alternator died and the truck started shutting down stuff to conserve the battery, although it was alarming to have the headlights shut off on their own on the freeway.

I'm hoping that is a simple solution like a main fuse instead of a bad alternator. I'm charging the battery overnight and will take a closer look in the morning. I'm going to start out with check voltage at the battery with the engine running to see if I get the 15 or so volts I should see. I'll do some more reading of the owner's manual and searching online in the morning.

Anyone have the same thing happen? Any suggestions other than towing it to the dealer? Thanks.

Ranb

 

If you put your truck into engineering mode then scroll through the menu it will show battery voltage before and after you start the engine so you can see if your alternater is putting out.

Plenty of youtube videos on how to use engineering mode.

 

There are 2 (or 3 since there is a second level 2) levels of load shedding with the engine running if the BCM detects low voltage. Headlights turning off is not one of them. It's more than likely you did not have enough voltage from the battery and it caused modules and electronics to behave erratically due to insufficient voltage.

 

How old is your battery? I have seen many wonky electrical issues, often comes back to bad battery, even at 3 years old. That would be my first suspect area.

 

The battery is the original, 2016. I ran the truck in engineering mode; the battery is at 11 volts. I did not think the battery could drag down the electrical system so much that the alternator could not power everything properly.

For the last year or so, the auto shut-off feature was keeping the engine running due to a "battery charging" or something like that when I was at a complete stop with the engine warm. Should that have been a clue that something was wrong with the battery?

Shopping for a new battery now. Thanks for the advice.

 

Clearly.

 

11 volts running or not running? The alternator powers the electrical load of the truck and charges the battery while the engine is running. Your battery may need replaced, given its age and other subsequent information, but it's also likely you got an issue with the charging system. The battery warning light on, while the vehicle was running, indicates there was a fault in the charging system. It is not an indicator for the battery.

 

You have an Alternator failure. That is why the Dash Lamp came on
There should be a Code P0621, 0625 or 0626 telling what part of the system failed.
A battery from 2016 is pushing the envelope bit for age and use and can help the Alternator fail from excessive charging intervals at high current levels by wearing down the Brushes and overheating the Alternator along with supplying the rest of the truck.
Replace with both a >charged< Battery and the Alternator before trying to start the engine.
If there are no other faults, the Dash Lamp will go out and no code set.
Don't do a code clear because it results in a Re-boot of the Computer you do not need.

 

The old battery was 11 volts running and not running.

I replaced the battery and it is at 11.9 volts stopped, and 11.8 volts while idling. After installing the new battery, I drove the truck for about five miles and the battery light came on along with the "service charging system" warning.

I'm going to charge the new battery overnight and see what happens tomorrow. The alternator is covered up with lots of crap under the hood. I'm hoping I don't need to take it out for replacement or repair. Will the codes in engineering mode tell me if it is the alternator or something else in the charging system that is giving me the warning message?

It is 13 miles from the Ford dealer near Bremerton to my home, I don't think the truck will make it to the dealer for diagnostics on the battery alone if the alternator is not working.

I did find this thread; https://www.f150forum.com/f2/2016-f1...521286/index3/

 

How to h*ll do you expect the battery voltage to be up when the Alternator is not charging?
It's just common sense.
It does not make a difference where the Alternator is located, it's not working.