Adaptive Cruise Braking - Soft Grinding Noise

[Fizzy]

I noticed on a recent road trip that when the Adaptive Cruise Control is operating, and has to the slow the vehicle down to an almost dead stop, that there's a soft grinding sound, very similar to the sound you hear when ABS is operating. Doesn't happen any other time when braking manually.

Anyone else notice that too?

 

[JAMADOR]

Yep, our 2018 Max has always done it, just never thought to ask about it. Only when the ACC brakes, never any other time.

 

[lobsenza]

The ACC brakes the same way the ABS does, so the sound is the same.

 

[Fizzy]

Yep, our 2018 Max has always done it, just never thought to ask about it. Only when the ACC brakes, never any other time.

It's odd that I've never noticed it before honestly. Probably had the music up too loud! I was worried it was a seized/locked up IWE.

The ACC brakes the same way the ABS does, so the sound is the same.

Makes sense. It's just much softer than when ABS is intervening - likely because when ABS kicks in it's a critical event and being more forecful than the gentle slowing of ACC.

 

[Password]

Mine has been doing it for the last 6 years. I've never asked the service advisor about it.

 

[Mr Big]

My 2019 does not have any noise, even when I let it brake hard at the stoplight, When ACC is activated. I wonder if it's brake pad noise? How many miles on the Expy?

 

[wakeboarder]

It is normal. This is in the ACC portion of the manual. “Note: The brakes may emit noise when applied by the system.”

 

[Mr Big]

It is normal. This is in the ACC portion of the manual. “Note: The brakes may emit noise when applied by the system.”

I immediately did a brake job and switched to high performance ceramic pads, when I purchased my EX.
My stopping power is no less than with the semi-metallic pads Ford puts in. The heat range is the same as the Ford spec'd semi-metallic pads. That's probably why I have no noise, compared to others.

 

[HISHONOR]

My 2018 Limited has always done it. Always makes my wife think we’re about to crash when we’re actually stopping, even in slow highway bumper to bumper traffic.

 

[khammer]

I concur. same for both 2018s that I have had. I would describe the sound the exact same way as you did.

 

[JAMADOR]

Glad to hear from multiple that it's normal. Its always bugged me, but I don't use ACC too much in traffic

 

[Mr Big]

After listening to many responding about grinding noise, it seems obvious that Ceramic pads will solve the problem. I know there may be certain conditions where one may not want to switch. But there are advantages in most cases.
I drive locally and take many short road trips and a couple of long trips.
With that said, I mainly switched to eliminate friction, wear, heat and even wear on the rotors. I've noticed absolutely no difference in feel, except it is a lot smoother. I did go with a high-quality set and they cost me $100 to have then installed and rotate the tires. My total cost was under $200.

 

[Fizzy]

After listening to many responding about grinding noise, it seems obvious that Ceramic pads will solve the problem. I know there may be certain conditions where one may not want to switch. But there are advantages in most cases.
I drive locally and take many short road trips and a couple of long trips.
With that said, I mainly switched to eliminate friction, wear, heat and even wear on the rotors. I've noticed absolutely no difference in feel, except it is a lot smoother. I did go with a high-quality set and they cost me $100 to have then installed and rotate the tires. My total cost was under $200.

The griding noise has nothing to do with the pads or discs/rotors. This is clear because none of our vehicles are grinding under manual braking.

It's the same noise that's made by the ABS system, because it's the same system used by both ABS and ACC to modulate brake pressure. The part making the noise is called the hydraulic modulator (colloquially the ABS pump) - basically a motor/pump that takes over controlling brakes by pumping or releasing brake fluid.

Every vehicle I have ever owned since the 1980s with ABS makes this same noise. I was just surprised to learn the ACC used the same braking pump as the ABS, but in hindsight it makes perfect sense.

 

[Mr Big]

The griding noise has nothing to do with the pads or discs/rotors. This is clear because none of our vehicles are grinding under manual braking.

It's the same noise that's made by the ABS system, because it's the same system used by both ABS and ACC to modulate brake pressure. The part making the noise is called the hydraulic modulator (colloquially the ABS pump) - basically a motor/pump that takes over controlling brakes by pumping or releasing brake fluid.

Every vehicle I have ever owned since the 1980s with ABS makes this same noise. I was just surprised to learn the ACC used the same braking pump as the ABS, but in hindsight it makes perfect sense.

My point is: "My Expedition does NOT make a grind noise, when using ACC". There is absolutely no noise when the brakes are applied. Same goes for hill assist. There's no noise when the brakes are applied going down a hill. They are totally silent. The grinding noise may be normal to some and not to others.

 

[HISHONOR]

The noise made when using the ACC is not the same as the ”grinding” noise brake pads make. The sound is more like rubber pads quickly rubbing against each other with the haptic feel of the truck suddenly braking.

 

[Mr Big]

The noise made when using the ACC is not the same as the ”grinding” noise brake pads make. The sound is more like rubber pads quickly rubbing against each other with the haptic feel of the truck suddenly braking.

It's rather obvious that others who are experiencing this grinding noise may have a problem. I'm not sure if it is certain years, but, according to Ford, there should be no noise. Again, mine is dead quiet. It might be advisable, especially if still under a bumper to bumper, extended or 3rd party warranty, to have it checked out before it develops into something worse.

 

[Fizzy]

The noise made when using the ACC is not the same as the ”grinding” noise brake pads make. The sound is more like rubber pads quickly rubbing against each other with the haptic feel of the truck suddenly braking.

It's normal operation - disregard. The sound is the hydraulic modulator in the braking system doing the job your foot would do on the pedal.

 

[Mr Big]

It's normal operation - disregard. The sound is the hydraulic modulator in the braking system doing the job your foot would do on the pedal.

That doesn't explain why some drivers hear the noise while others like me have no noise whatsoever. First, I thought the noise may be because of different models. But I've read some Platinum owners have the noise and others don't. My Expedition is a 2019 with HD Tow, yours is a 2020 with HD Tow. If you have the noise, what has changed?

 

[Fizzy]

That doesn't explain why some drivers hear the noise while others like me have no noise whatsoever. First, I thought the noise may be because of different models. But I've read some Platinum owners have the noise and others don't. My Expedition is a 2019 with HD Tow, yours is a 2020 with HD Tow. If you have the noise, what has changed?

Google it. I did, and there's countless posts about this. Every Ford forum I can find has this same thread - F150s, Explorers, etc - anything with ACC. And the overwhelming consensus is everyone (except you) has it, and it's standard expected behaviour.

Not sure why yours is the exception. It's not your pads though as the noise is not from the rotors or pads - it's the hydraulic modulator, because it's the same noise when ABS is activated, only softer because it's not a critical full braking event.

 

[wakeboarder]

That doesn't explain why some drivers hear the noise while others like me have no noise whatsoever. First, I thought the noise may be because of different models. But I've read some Platinum owners have the noise and others don't. My Expedition is a 2019 with HD Tow, yours is a 2020 with HD Tow. If you have the noise, what has changed?

There is a note in the manual (page 244 in 2019) that says the noise is normal. Mine doesn’t always make the noise, but it does it frequently. It seems to be associated with harder braking. It is not so hard that it makes you think the ABS is engaging, but it is harder than I would normally brake.