Greetings from Calgary, Alberta

My beloved 2015 F-150 V8 stalled in the middle of a busy intersection at 7 am this morning causing a huge clusterf*ck. it completely lost power and I had no gas, brakes, I couldn't even turn the steering wheel. I was attempting to turn left and a city bus almost ripped the left front side of my truck off. Needless to say after panicking and other drivers honking at me I was able to get the truck restarted and drive it to a parking lot nearby. I was completely frustrated and in shock because I almost caused a huge train wreck. My truck barely has 35,000 km on it so I'm even more frustrated that something like this would happen. I ended up getting it towed to the nearest Ford dealership because I was too scared of it stalling again if I attempted to drive it. So now I wait...the truck is at the dealership and I'm really curious to see what the outcome is. What a way to start the day and completely ruin it at the same time! Ugh! I will give an update when I know more. Somebody up above was looking out for me today.

 

its good that no one got hurt.

But your engine stalled... this does not directly affect steering or brakes.

Steering - you still had manual steering unless the key was out and the column locked. You have electric power steering so I would have thought that the power steering would still be available, unless the issue is a short in the electrical system? Or a short in the steering column that made the truck think you turned it off?

The brakes - you always have the ability to apply the brakes with the brake pedal. Always. You might loose boost when the engine is off, once the vacuum in the vacuum booster is depleted. But the vacuum booster is sized to apply the brakes 5 times with boost before running out of vacuum. (unless you have a leak in your vacuum booster?).

So, when you say no brakes or steering - do you mean no power boost for either???

 

You may be right, but sometimes I'm sitting in a parking lot waiting for the wife to shop and I want to use the buttons on the wheel for the radio but they're upside down. I turn the key on and shift into drive. Turning the wheel is not easy. Many times I just start the truck to get the buttons in the right position. If I remember, it used to be easier with older vehicles to manhandle the wheel in a stall. Nowadays it's much harder.

Hmm... I'm older too. Maybe It's me??

 

Hogwash!
It sure does directly affect the steering. If the engine isn't running and the key is turned all the way clockwise the power assist isn't on. Trying to steer without power assist is very difficult unless you are moving at a decent clip.

 

you should look up the definition of "directly" vs "indirectly".

In older vehicles the power steering was powered by a pump that was run by a belt from the engine. If the engine stalled, you lose all power steering because the pump stops. This was a direct effect.

My point was that there is no direct connection from the engine to the power steering. The power steering is now electric and powered from the battery.

I cannot tell you for sure what is the indirect affect of having the engine stall on the power steering. Theoretically the power steering could still be powered because your 12 V battery is still connected. But, perhaps, they turn off the power steering to avoid a high load on the 12V system without the engine running. Or perhaps, as I suggested before, the cause of the engine stall also caused the power steering to fail.

But these are all indirect links between the engine running and the steering system.

 

You don't own a 2015-17 F-150 so you are guessing.

I simulated the same situation the OP experienced and cut the engine off in a big parking lot and the power assist was disabled but I was still able the turn the truck in a circle but I am 6'3" and 240 lbs though.

 

But what happens when you turn the key back on? Of course it will shut down with the key off.

 

I would prefer the phrase "using my vast experience with advanced automotive systems, power nets, and CAN to give an educated opinion", but yes... in the end all I can do is guess about what happened in a truck I've never seen on a day when I wasn't present.

Your simulation is good data to have, but if you simulated the stall by turning the key then you were either in accessory mode or "off". The OP did not turn his key so this is not quite the same scenario. Even if you turned the key off and then back to "run" without starting, this is not quite the same as the truck's ECUs will know the key was turned off.

The best way to simulate this would be to perhaps remove the fuel pump fuse to get the engine to stall.
But even then it might not be 100% accurate until we know the source of the stall. It is possible that the engine stalled because the wiring in the steering column is chafed and the truck thought he turned off the key (in which case your experiment was indeed accurate). But there are probably 100s (1000s?) of other possible causes of an engine stall and we don't know for sure what happened.

If it were my truck, and I had access to advanced tools, and I could reproduce the failure.... I would reproduce the failure while taking CAN logs to see what is the exact vehicle state at that moment.

But of course I can't do 2 of those 3 things, so I'm left "guessing" on an online forum.

 

update?