"Park Brake Limited Function, Service Required" after truck rolls backward toward a drop-off

[iam2sam]

I took my 2025 XL 2.0 (w/4k tow pkg) to our Virginia property for a week and a half (just returned tonight). While the trip was completed successfully, the truck proved to be entirely inadequate for that property, but I will post most of that in another thread; this one is about one particular, very troublesome, issue. After arriving, I parked to truck on a moderate grade, facing uphill. I put the shifter in Park, then shut off the engine. I then realized that I had neglected to set the parking brake, so I did so, without restarting the engine. No message appeared on the LCD display on the speedo panel, which seemed reasonable, because the ignition was off. However, the red "BRAKE" letters lit up, which duplicated what happens when I set the brake with the ignition on and receive confirmation on the LCD display, so I made what I think was a reasonable assumption that the parking brake had engaged normally. I might ordinarily have restarted it before applying the brake, but I had just completed and 8 hour drive, was dead tired, and thought what I did was adequate. I exited the truck and was talking to my wife (who had driven a different vehicle) with my back to my driver's door, when she let out a scream. I turned back to the Maverick to find that it was rolling backward down the slope, toward a very steep embankment that would have done extensive damage had the truck gone over it. Fortunately, it stopped before that point (the grade lessens before the embankment). Badly shaken, I got back in, started it up, and was presented with this message on the LCD ""Park Brake Limited Function, Service Required". The truck was serviced at the Ford dealership from which I bought it, the trailer towing signal issue fix was applied, and it was confirmed to be up to date on all other fixes as of May 22, a week before this trip. WTLF was this all about? Why would the red "BRAKE" legend display in the same manner it does when the brake is successfully applied, if that was not the case? Also, the transmission was in "PARK". How the F did it glide backward down that slope for 10-12 feet without trashing the transmission? As result of this incident and the other inadequacies, I have already decided to upgrade to some other truck, but I would like to get a reasonable explanation of what likely was the cause, and what steps I should take in the meantime.

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[Glen Baker LLC]

That is definitely an "OH " moment.
I'm glad you're okay and you were able to catch it before it went over the edge.

 

[notfast]

How the F did it glide backward down that slope for 10-12 feet without trashing the transmission?

Ford Recall 25C69 is for the integrated park module, but it only covers hybrids. Pretty concerning to hear about virtually the same problem on an EcoBoost.

Maybe someone else can chime in, but I'm not sure if the parking brake engages unless the vehicle is running or in key-on-engine-off.

 

[Pointyears]

Ford Recall 25C69 is for the integrated park module, but it only covers hybrids. Pretty concerning to hear about virtually the same problem on an EcoBoost.

Maybe someone else can chime in, but I'm not sure if the parking brake engages unless the vehicle is running or in key-on-engine-off.

If it’s quiet out, you can actually hear the electric brake engaging.

 

[RatherB.Fishin]

seems like the parking brake wasn't fully applied, for whatever reason. it's all electronic so perhaps it glitched out and didn't apply enough pressure. doesn't explain why it slipped off the parking pawl though.

 

[MavStangVa]

A question for you. Had you opened the driver's door before setting the brake? I did exactly what you did in my drive which has a decent slope near the end of it by the back yard. I had already opened the door and realized I hadn't set the brake but my foot was still on the brake pedal. I set the parking brake and took my foot off the pedal and the truck rolled about 6" before I stomped the pedal. I restarted the truck set the parking brake then turned it off and it was fine. I'm wondering if the BRAKE light comes on with the door open even though the brake didn't set. I haven't attempted to recreate it and usually park further back away from the slope. But I now always set the parking brake before I turn the truck off.
EDIT: Just tried to duplicate today in my driveway and it worked perfectly. Maybe the first time was just a glitch but I am not comfortable with a safety feature having a glitch. I will bri it up when I FINALLY am able to have the trailer recall done.

 

[matmondro]

In my experience, the parking brake will engage when the truck is off, even with the key out of the ignition. I've done it standing outside of the truck, with the driver's door open, like in your situation. I can hear the park brake solenoid whir when I engage it.

However, whatever happened here does not seem normal at all and IMO requires immediate attention from the dealer. Is there a chance there's a bug in that new software for the trailer module recall? That's the only explanation I can think of. Glad you're okay, that sounds scary AF!!

I'd *carefully* try to see if I can recreate the fault again.

 

[iam2sam]

Ford Recall 25C69 is for the integrated park module, but it only covers hybrids. Pretty concerning to hear about virtually the same problem on an EcoBoost.

Maybe someone else can chime in, but I'm not sure if the parking brake engages unless the vehicle is running or in key-on-engine-off.

Regarding engagement, this is what the manual has to say:
APPLYING THE ELECTRIC PARKING BRAKE
The red warning lamp flashes during operation and illuminates when the
parking brake is applied
Note: You can apply the electric parking brake when the ignition is off.
Note: The electric parking brake could apply when you shift into park (P). See
Park (P).
So, it would appear that it can be applied with power off, although the rest of that seems a bit ambiguous. IMO, ambiguity is not a desirable quality in describing critical vehicle functions. I have made the tentative decision to bite the price difference bullet and move to a new Tacoma TRD Off-Road.

 

[MavStangVa]

Regarding engagement, this is what the manual has to say:
APPLYING THE ELECTRIC PARKING BRAKE
The red warning lamp flashes during operation and illuminates when the
parking brake is applied
Note: You can apply the electric parking brake when the ignition is off.
Note: The electric parking brake could apply when you shift into park (P). See
Park (P).
So, it would appear that it can be applied with power off, although the rest of that seems a bit ambiguous. IMO, ambiguity is not a desirable quality in describing critical vehicle functions. I have made the tentative decision to bite the price difference bullet and move to a new Tacoma TRD Off-Road.

I don't blame you. If I had your incident I would never trust it again.

 

[Scott Asheville]

This story reminds me of something I was taught way back in the 1960s as I learned to drive with manual transmissions. We were taught, when parking on slopes, to always turn the wheel so the vehicle would back into something (like a curb or a tree) that would stop it. Because back then, vehicles would pop out of gear, or parking brakes would fail - all kinds of crazy stuff. It was the era of "it's a good day if my car works".

 

[Glen Baker LLC]

A question for you. Had you opened the driver's door before setting the brake? I did exactly what you did in my drive which has a decent slope near the end of it by the back yard. I had already opened the door and realized I hadn't set the brake but my foot was still on the brake pedal. I set the parking brake and took my foot off the pedal and the truck rolled about 6" before I stomped the pedal. I restarted the truck set the parking brake then turned it off and it was fine. I'm wondering if the BRAKE light comes on with the door open even though the brake didn't set. I haven't attempted to recreate it and usually park further back away from the slope. But I now always set the parking brake before I turn the truck off.

Even that shouldn't have happened. You should absolutely be able to set your brake, after you've turned the truck off and open the driver's door.
Have you tried to recreate the incident/situation?

 

[MavStangVa]

Even that shouldn't have happened you should still be able to set your brake, after you've turned the truck off and open the driver's door.
Have you tried to recreate the incident/situation?

I edited the original post. I did try to recreate it today.

 

[Ryom]

I edited the original post. I did try to recreate it today.

The parking brake takes a moment to engage, it may be possible that the service brakes were released before the PB was engaged which over-rode the action, leaving it off and the vehicle able to roll?

My '25 hybrid will apply PB on any slight incline automatically, so it's not something I typically need to futz with.

 

[HeyBales]

And to that situation that it seems 25/26MY are more willing to apply the EPB on the least of slopes - seemed those discussions was on the hybrid, around the recall it got.

Were there EB drivers that see the same auto-apply?

I know the application of the EPB is pretty quick compared to the line draw across the screen - I guess that is so long for the driver to see the fact it says it's happening.

It is concerning for the EB neither the parking pawl, which should have engaged since the EPB was done after the fact, or the EPB didn't engage enough.

That should be reported also, just in case a few others have popped up - and a situation needs addressed.

What if the EPB system isn't doing accurate measurements to keep whatever mm distance from pads to rotors - so it did run the motors out and thought it had pressure?
Seems like that would be bad for normal braking too, at least for the rear to be helping in the effort.

 

[matmondro]

Another thing I'll add after reading the original post again... aside from the parking brake, the parking pawl should have automatically engaged anyways as soon as you opened the drivers door. That's a safety feature nowadays after that actor got ran over by his own truck some years ago. So the fact it seems like that didn't happen is also concerning.

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