Drive Mode Selection...System Fault

If we just turn on the electronics of our new rig, we get the error in the screenshot. If we turn on the engine like normal, it doesn’t show up. Is this a common message if you only turn on the battery? Google, oddly, doesn’t seem to give me anything....

that’s odd, looks like you have two dealer items. Or it could be in relation to your USB pulse problem, might have an electrical gremlin.

JExpedition07 said:

that’s odd, looks like you have two dealer items. Or it could be in relation to your USB pulse problem, might have an electrical gremlin.

Click to expand...

Those are the worst types of gremlins...

I don't think its a gremlin or a problem. It's exactly what I'd expect for accessory only power. Not all the electronics and sensors are powered, or if they are, some sensors are reporting out of range faults, and some stuff isn't going to respond correctly to its commands*. In other words, your truck is thinking there's a whole bunch of failed electronics because it's not seeing the expected CAN bus traffic because those computers are unpowered. OR the truck is measuring things like oil pressure, cam shaft rotation speed, brake fluid pressure, vacuum pressure, commanded fan speed vs actual fan speed, etc, etc and finding they're way out of the expected range and concluding there's a bunch of serious problems. Yes, if the display software folks had done their job, all those error codes would be suppressed in accessory power mode. Welcome to ownership of a first year model!

*It's actually some combination of all three.

And to prove my hypothesis, you'll notice the little battery icon is illuminated (look below the "OK" box). That means the alternator isn't providing the expected output. Well, the engine's off, so the accessory belt isn't moving, so the alternator isn't spinning and it's output is 0V. But the truck is thinking, "OMG! The alternator output is 0V!! Why the alternator output shouldn't be 0V! I've gotta warn somebody that there's a problem with the alternator!!" In a perfect world, it'd be programmed to check for accessory power mode before concluding that there's something wrong with the alternator.

That was what I was wondering as well, almost like a check engine light when you turn a key over but don’t start the truck due to a lack of oil pressure.

shane_th_ee said:

And to prove my hypothesis, you'll notice the little battery icon is illuminated (look below the "OK" box). That means the alternator isn't providing the expected output. Well, the engine's off, so the accessory belt isn't moving, so the alternator isn't spinning and it's output is 0V. But the truck is thinking, "OMG! The alternator output is 0V!! Why the alternator output shouldn't be 0V! I've gotta warn somebody that there's a problem with the alternator!!" In a perfect world, it'd be programmed to check for accessory power mode before concluding that there's something wrong with the alternator.

Click to expand...

Thanks @shane_th_ee

I was wondering if it was simply a really poorly worded message that was needlessly displayed when the truck was in accessory mode.

Here's the question though...can anyone else try this on another 2018 Expedition? Any other owners or units on the lot? When put into accessory mode, do you get the same "error?" Thanks!

So I noticed the top left gauge is oil pressure.
How/why is it showing a reading if your engine is off?

An engine that was running recently should still have SOME oil pressure. Ford may still have the oil pressure switch, not sensor, that has the gauge showing "OK" since there is some pressure. The transmission is also quite warm, and the coolant isn't cold, this picture is from an engine that was quite recently driven.

gremlin i bet because the above stated the alt is not producing so its causing faults...but does Seem WEIRD in wording