Mystery Noise under front when Bronco parked after opening door

[Lil Red Broncette]

My newly received Black Diamond is doing this and I can't figure out what it is.

For reference a Black Diamond, 2.3L, Manual Trans, Squach.

The most predictable time it occurs is when I do this.

-Vehicle parked and locked and been sitting some time (not sure how long, but 20 min or longer seems enough)
-I unlock with the keypad on the door.
-I open the door.

I then hear something running for 5 seconds-ish that I can best describe as sounding like when you turn on a printer and you hear the print head move to the end of its travel then back except this has metallic sound to it. It seems to come from underneath the front of the vehicle. It sounds like something moves one way then back.

I can close lock the door and open again but it won't repeat unless I go away for some time.

I am sure it happens at other times, but the sequence above is most predictable. Most of the other times I hear it is after driving when I park it, get out, then lock the door.

Because I can't just make it happen repeatedly I can't find the source.

I think it has something to do with the Black Diamond package, Manual Trans or Squach package since my Bronco Base which is non-squach auto trans does not make the sound. I don't think it is something wrong, just a sound I've never heard from a car.

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[Classic28]

Electric parking brake?

 

[dgorsett]

Yeah, happens all the time w/ my BB 2.3 AUTO. It's something coming to life after a sustained shut down, normal. Funny it doesn't happen w your base. And I seldom set the brake.

 

[Cwill79]

I get it on my base. Strange. I thought it was a bad connection on the door chime at first. Ha. The printer starting up is a good call on the sound tho.

 

[DefNotBuddyLee]

If it is the sound I am thinking of, I believe that is the car getting out of "sleep" mode (at least that is what I previously understood from another post). Not sure the specific part making the noise, but I hear it regularly from being near with my keyfob to other random things when working on my Bronco after it has been shutdown for 10-15 minutes.

 

[dgorsett]

Service manuals for years have said step 1 disconnect battery....I seldom do it...on the Bronco it might be a good idea, it seems to have a mind of its own.

 

[RescueCheckPT2]

Mine does it too. It's a Ford thing, not just a Bronco thing. I had a 2014 Focus ST that did this too under the exact same conditions. I never looked into it really because everything functioned normally; but I do like the theory of "coming out of sleep mode".

As to why your base doesn't, all I can think is that it being an auto is the oddity. My Focus and Bronco are both manuals so maybe that has something to do with it.

 

[DropHunter]

Maybe this.

the fuel system is pressurized at unlock/open so it's primed and ready. This reduces extra cranking to start up, putting less strain on the starter & battery etc, in theory, making them last longer

 

[lapazleo]

The Bronco is not a car.

 

[AllthePonies]

The Bronco is not a car.

Per Wikipedia, a car is a wheeled motor vehicle that is used for transportation. Most definitions of cars say that they run primarily on roads, seat one to eight people, have four wheels, and mainly transport people instead of goods.

The Oxford Languages Google dictionary says that a car is “a four-wheeled road vehicle that is powered by an engine and is able to carry a small number of people.”

 

[Lil Red Broncette]

Electric parking brake?

Definitely not. I have enabled and disabled the parking brake and the brake is a different sound from a different area

 

[Lil Red Broncette]

As to why your base doesn't, all I can think is that it being an auto is the oddity. My Focus and Bronco are both manuals so maybe that has something to do with it.

Some with base and auto trans seem to have the same thing. Maybe it is more recognizable because I have this one in a garage and the other is outside. The base is at a different residence so won't be able to double check till I get there in a month or so. Still I would have thought I notice it with about 1200 miles on it, this BD I only have about 20 miles and it has been pretty obvious.

 

[Lil Red Broncette]

Maybe this.
the fuel system is pressurized at unlock/open so it's primed and ready. This reduces extra cranking to start up, putting less strain on the starter & battery etc, in theory, making them last longer

Usually the fuel system gets primed right when starting. Also that is a fuel pump sound originating back at the fuel tank.

 

[Lil Red Broncette]

If it is the sound I am thinking of, I believe that is the car getting out of "sleep" mode (at least that is what I previously understood from another post). Not sure the specific part making the noise, but I hear it regularly from being near with my keyfob to other random things when working on my Bronco after it has been shutdown for 10-15 minutes.

I wonder what it would be doing though? I guess I have to place some cameras to see if I can catch it in action.

If I were to make a wild guess, this may be for the Automatic Emergency Braking and/or maybe the stability control system. Vehicle ABS systems usually do some sort of self diagnostics after starting when just starting to move, but that doesn't involve applying brakes. My thinking is Automatic Emergency Brake system may be too obvious to do as it applies brakes so the self diagnostic intentionally runs when the vehicle believes it stopped at times intentionally when off. The sound could be it running thru its travel limits. On the other hand the 5 seconds plus of the sound, that seems kinda slow for an emergency activation.

Maybe the owners manual says something, maybe I should read it.

 

[DEC]

Sleep mode, my BMW does the same.

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