auto start stop and two random bumps

[Wolfman00]

so this is weird and seems like one or two others had this.

when auto stop is engaged, and engine shuts down-i hear a “thump”, then about a second later- another “thump”. you can feel it in the brake pedal.

with ass off, doesnt happen. only when the auto start stop is on.
i feel like its a function of it, but its annoying and i have no idea what it is. probably something small and dumb that vibrates though the truck.

its not the driveshaft slip joint, checked that.
its not the wastegate making its noises either. so i got those eliminated.

anyone have any ideas?

also- not eliminating the auto stop, i actually like it.

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[FX4Offroad]

Interesting. All I feel on mine is the rumble of the engine turning off and on. No additional bump.

 

[OregonRangerTremor]

No issues yet on my Ranger but I try to remember to always turn it off on start up. My Wife's Ford Transit Connect Van; it started to work randomly and now the auto shut off does not work. She also had a very hard clunk in the transmission and high revs. On warranty so took it to the Dealer. They could find nothing wrong and could also not find any means to get the auto stop feature to work again. They sent a bulletin to Ford for answers. That was 3-4 months ago and we have heard nothing. At least it's on "the record" so if a future problem occurs....we will hold Ford accountable for repairs.

 

[Motorpsychology]

No issues yet on my Ranger but I try to remember to always turn it off on start up. My Wife's Ford Transit Connect Van; it started to work randomly and now the auto shut off does not work. She also had a very hard clunk in the transmission and high revs. On warranty so took it to the Dealer. They could find nothing wrong and could also not find any means to get the auto stop feature to work again. They sent a bulletin to Ford for answers. That was 3-4 months ago and we have heard nothing. At least it's on "the record" so if a future problem occurs....we will hold Ford accountable for repairs.

There are over a dozen conditions that can prevent ASS from engaging: Transmission in Sport Mode, cold engine, steering wheel cocked at a certain degree are the most common. If the Battery Maintenance System (BMS)detects a preset low voltage, which isn't all that low, it will prevent the ASS from engaging. During the height of the pandemic, we weren't driving our previous 2018 Escape very often and the ASS stopped functioning until we took a long road trip. It started working again for a while, but quit again after we settled into our normal routine. Scrolling thru the driver info display, it showed ASS was off due to normal conditions.

 

[Wolfman00]

in the early days mine had a noticeable thump.
it doesn't now.

it is a function of the systems as it transfers brake pressures with the engine running/not running

i dont recall where there was a write up on it. a quick search i didnt see it in the owners manual or the tech manuals. but its out there somewhere.

ah ok. is this something that can be adjusted to quiet down? seems like its louder when its cold. (or its just me)

 

[Wolfman00]

has anyone else run into this?

 

[Motorpsychology]

has anyone else run into this?

Not on my Ranger, but I had a '72 GMC that had a bad wheel bearing and would thump when the brakes were applied.
Yeah, long ago in a galaxy far away, but the design is still much the same.

 

[Wolfman00]

anyone else?

 

[Wolfman00]

any updates from anyone?

 

[VegasRanger]

I disabled A/S/S a long time ago.

 

[Wytchdctr]

That honestly sounds like it might be warranty work. A lot of us here have ASS turned off, but it thumping after shutdown/feeling it in the brakes can't be good.

 

[Wolfman00]

That honestly sounds like it might be warranty work. A lot of us here have ASS turned off, but it thumping after shutdown/feeling it in the brakes can't be good.

my dealer said “it was normal”. well the 3 i test drove didnt do it. they didnt want to work on it. its going to a new dealer anyway to get my seat fixed correctly

 

[Wytchdctr]

my dealer said “it was normal”. well the 3 i test drove didnt do it. they didnt want to work on it. its going to a new dealer anyway to get my seat fixed correctly

Crap. Is it loud enough to catch on video?

 

[Wolfman00]

Crap. Is it loud enough to catch on video?

probably not. you can feel it in the brake pedal though. it could be something with the brake booster, as i know that system has a role in the auto start function.
maybe its needs a bleed and the bumps are the pump trying to prime itself/ but cant? beats me. i know im not the only person who has had this. i doubt its serious, just super annoying at a stop light.

 

[Motorpsychology]

probably not. you can feel it in the brake pedal though. it could be something with the brake booster, as i know that system has a role in the auto start function.
maybe its needs a bleed and the bumps are the pump trying to prime itself/ but cant? beats me. i know im not the only person who has had this. i doubt its serious, just super annoying at a stop light.

Are you saying the thump is felt only in the brake pedal? Mine will shudder slightly when the ASS shuts off and again when it restarts, but that is felt in the whole truck; passengers can notice it too.

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