Cayenne Random Braking
11-15-2018, 05:09 PM
#1
Rennlist Member
Thread Starter
Cayenne Random Braking
I've had my 2011 CTT for about a year now. Twice since i've had it, the car has braked suddenly on its own for a second and then resumed normally. In other words, I was driving along around 30 - 40mph with my foot on the gas and the brakes came on hard. It felt like someone slammed on the brake pedal for a second and then let go. A light in the cluster came on referencing the ACC system but no faults or anything. Any idea why this happened? My car has ACC, but I wasn't using cruise control when it happened.
My car is in for service now and they haven't found anything related to this issue. They are replacing the entire steering column to get rid of a howling noise i have when moving the wheel up and down. Thank god for CPO!
Any thoughts would be appreciated.
Thanks!
My car is in for service now and they haven't found anything related to this issue. They are replacing the entire steering column to get rid of a howling noise i have when moving the wheel up and down. Thank god for CPO!
Any thoughts would be appreciated.
Thanks!
11-15-2018, 05:21 PM
#2
Drifting
Cayennes with ACC also have PAS (Porsche Active Safety) integrated as part of that system. PAS will detect something suddenly in your path that’s too close and will apply the brakes, quite abruptly! When this happens the little warning light on the instrument cluster will briefly illuminate.
That same warning light will also come on if you’re following someone too close, although it won’t apply the brakes in this case (unless the vehicle you were following too close suddenly braked and cut the distance even closer).
So if your brakes have suddenly been applied as you described, either something in your path caused it which PAS detected, or the system is malfunctioning or falsely detecting something. I do know that the ACC system has a very specific calibration process that only a dealer can address with special equipment if it gets out of spec (usually through an impact of some sort with the front end where the ‘eye’ is).
That same warning light will also come on if you’re following someone too close, although it won’t apply the brakes in this case (unless the vehicle you were following too close suddenly braked and cut the distance even closer).
So if your brakes have suddenly been applied as you described, either something in your path caused it which PAS detected, or the system is malfunctioning or falsely detecting something. I do know that the ACC system has a very specific calibration process that only a dealer can address with special equipment if it gets out of spec (usually through an impact of some sort with the front end where the ‘eye’ is).
11-15-2018, 05:35 PM
#3
Rennlist Member
Thread Starter
Cayennes with ACC also have PAS (Porsche Active Safety) integrated as part of that system. PAS will detect something suddenly in your path that’s too close and will apply the brakes, quite abruptly! When this happens the little warning light on the instrument cluster will briefly illuminate.
That same warning light will also come on if you’re following someone too close, although it won’t apply the brakes in this case (unless the vehicle you were following too close suddenly braked and cut the distance even closer).
So if your brakes have suddenly been applied as you described, either something in your path caused it which PAS detected, or the system is malfunctioning or falsely detecting something. I do know that the ACC system has a very specific calibration process that only a dealer can address with special equipment if it gets out of spec (usually through an impact of some sort with the front end where the ‘eye’ is).
That same warning light will also come on if you’re following someone too close, although it won’t apply the brakes in this case (unless the vehicle you were following too close suddenly braked and cut the distance even closer).
So if your brakes have suddenly been applied as you described, either something in your path caused it which PAS detected, or the system is malfunctioning or falsely detecting something. I do know that the ACC system has a very specific calibration process that only a dealer can address with special equipment if it gets out of spec (usually through an impact of some sort with the front end where the ‘eye’ is).
Last edited by GBX; 11-15-2018 at 07:29 PM.
11-15-2018, 09:35 PM
#4
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Cayennes with ACC also have PAS (Porsche Active Safety) integrated as part of that system. PAS will detect something suddenly in your path that’s too close and will apply the brakes, quite abruptly! When this happens the little warning light on the instrument cluster will briefly illuminate.
That same warning light will also come on if you’re following someone too close, although it won’t apply the brakes in this case (unless the vehicle you were following too close suddenly braked and cut the distance even closer).
So if your brakes have suddenly been applied as you described, either something in your path caused it which PAS detected, or the system is malfunctioning or falsely detecting something. I do know that the ACC system has a very specific calibration process that only a dealer can address with special equipment if it gets out of spec (usually through an impact of some sort with the front end where the ‘eye’ is).
That same warning light will also come on if you’re following someone too close, although it won’t apply the brakes in this case (unless the vehicle you were following too close suddenly braked and cut the distance even closer).
So if your brakes have suddenly been applied as you described, either something in your path caused it which PAS detected, or the system is malfunctioning or falsely detecting something. I do know that the ACC system has a very specific calibration process that only a dealer can address with special equipment if it gets out of spec (usually through an impact of some sort with the front end where the ‘eye’ is).
And more info: https://www.porsche.com/middle-east/...tive-safe-pas/ (from Nigeria? They want to send a certified check... )
And in the Macan (same system): https://www.porsche.com/internationa...tive-safe-pas/
What you're feeling is the "jolt".. note that is NOT the same as active braking, it's done just to get you to pay attention to driving.. I had it happen once..
11-16-2018, 02:40 AM
#5
Rennlist Member
The thread starter has a 2011 model, and the manuals and web pages linked above regards the 2014- models.
Are you sure the 2011 model also has PAS?
Cheers,
Tore
Are you sure the 2011 model also has PAS?
Cheers,
Tore
11-16-2018, 10:02 AM
#6
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First thing I did when I got mine was disable PAS. You can disable it through the regular menu in the instrument cluster. PAS, like ACC, suffers from assuming that things that aren't in your way, are. Namely, I have found that cars in front of you that exit your lane, enter a turn lane, and then slow down, will really upset ACC/PAS. Even though the car ahead of you is in a lane to your right/left, the car still "sees" it as in your way and will come to a damned stop in the middle of the road while they turn, if you let it.
11-16-2018, 10:12 AM
#7
Rennlist Member
Cayennes with ACC also have PAS (Porsche Active Safety) integrated as part of that system. PAS will detect something suddenly in your path that’s too close and will apply the brakes, quite abruptly! When this happens the little warning light on the instrument cluster will briefly illuminate.
That same warning light will also come on if you’re following someone too close, although it won’t apply the brakes in this case (unless the vehicle you were following too close suddenly braked and cut the distance even closer).
So if your brakes have suddenly been applied as you described, either something in your path caused it which PAS detected, or the system is malfunctioning or falsely detecting something. I do know that the ACC system has a very specific calibration process that only a dealer can address with special equipment if it gets out of spec (usually through an impact of some sort with the front end where the ‘eye’ is).
That same warning light will also come on if you’re following someone too close, although it won’t apply the brakes in this case (unless the vehicle you were following too close suddenly braked and cut the distance even closer).
So if your brakes have suddenly been applied as you described, either something in your path caused it which PAS detected, or the system is malfunctioning or falsely detecting something. I do know that the ACC system has a very specific calibration process that only a dealer can address with special equipment if it gets out of spec (usually through an impact of some sort with the front end where the ‘eye’ is).
I've seen the yellow warning from ACC when the gap is closer than it'd like. But never had any sudden/severe automatic brake application.
ACC during stop-and-go traffic is amazing, the way it slows nearly to a stop and then creeps along, trying not to make a hard stop... and resuming with traffic. It's really something. Trouble is, the gap it wants to keep is much wider than I'd like, given the horrifically aggressive lane-changers around the DC metro area. But even with lane-hoppers it successfully applies braking.
But then I'm guessing what's in my '17 doesn't have a direct parallel to that of an '11.
I'm thinking that if you have ACC that the camera/sensors might be having problems. I've not seen any of the service literature on how they test/adjust the ACC system.
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11-16-2018, 11:26 AM
#8
Drifting
I've driven my '17 GTS in a rather 'spirited fashion' and only once have I had the sudden red warning flash on the MFD. It was a sudden slow-down on the SB I-95 ramp onto 495W along the top side of the beltway. It didn't get to the point of actually applying the brakes "for me" as I swerved QUITE aggressively to avoid the impending collision. But it certainly got my attention! It happened so quickly I didn't really get a good memory of it. I don't recall if I was in active ACC mode or not.
I've seen the yellow warning from ACC when the gap is closer than it'd like. But never had any sudden/severe automatic brake application.
ACC during stop-and-go traffic is amazing, the way it slows nearly to a stop and then creeps along, trying not to make a hard stop... and resuming with traffic. It's really something. Trouble is, the gap it wants to keep is much wider than I'd like, given the horrifically aggressive lane-changers around the DC metro area. But even with lane-hoppers it successfully applies braking.
But then I'm guessing what's in my '17 doesn't have a direct parallel to that of an '11.
I'm thinking that if you have ACC that the camera/sensors might be having problems. I've not seen any of the service literature on how they test/adjust the ACC system.
I've seen the yellow warning from ACC when the gap is closer than it'd like. But never had any sudden/severe automatic brake application.
ACC during stop-and-go traffic is amazing, the way it slows nearly to a stop and then creeps along, trying not to make a hard stop... and resuming with traffic. It's really something. Trouble is, the gap it wants to keep is much wider than I'd like, given the horrifically aggressive lane-changers around the DC metro area. But even with lane-hoppers it successfully applies braking.
But then I'm guessing what's in my '17 doesn't have a direct parallel to that of an '11.
I'm thinking that if you have ACC that the camera/sensors might be having problems. I've not seen any of the service literature on how they test/adjust the ACC system.
Before I took delivery of my 2011 CTT, the ACC system required a calibration. On my extensive test drive I noticed the ACC system would automatically disable from time to time, displaying a fault on the MFD. Porsche Charlottesville had to send it over to Porsche Midlothian (Euroclassics) to get it calibrated because it required some special piece of equipment to do it (?), and Charlottesville's was down for maintenance at the time. They said it took 3-4 hours to properly calibrate with that special tool/equipment (whatever it is, I didn't ask). So it sounds like a fairly intense process? It came back perfect, never had another issue with it.
Last edited by CarGuyNVA; 11-16-2018 at 01:42 PM. Reason: additional info
11-16-2018, 11:28 AM
#9
Drifting
The 2011 model ABSOLUTELY does have PAS when equipped with the ACC option, no question. My 2011 CTT had it and it intervened to the point of automatic braking twice during my ownership. It addresses ACC/PAS in the 2011 owner's manual as well.
11-16-2018, 02:56 PM
#11
Rennlist Member
Thread Starter
Yeah, I had mine apply the brakes twice, both times were when vehicles swerved right in front of me across my line of travel. Once was on 95 coming down from B'more, and once on 66. When it does intervene to the point it applies the brakes, it scares the hell out of you!! It's very sudden and abrupt. It sure gets your attention!
Before I took delivery of my 2011 CTT, the ACC system required a calibration. On my extensive test drive I noticed the ACC system would automatically disable from time to time, displaying a fault on the MFD. Porsche Charlottesville had to send it over to Porsche Midlothian (Euroclassics) to get it calibrated because it required some special piece of equipment to do it (?), and Charlottesville's was down for maintenance at the time. They said it took 3-4 hours to properly calibrate with that special tool/equipment (whatever it is, I didn't ask). So it sounds like a fairly intense process? It came back perfect, never had another issue with it.
Before I took delivery of my 2011 CTT, the ACC system required a calibration. On my extensive test drive I noticed the ACC system would automatically disable from time to time, displaying a fault on the MFD. Porsche Charlottesville had to send it over to Porsche Midlothian (Euroclassics) to get it calibrated because it required some special piece of equipment to do it (?), and Charlottesville's was down for maintenance at the time. They said it took 3-4 hours to properly calibrate with that special tool/equipment (whatever it is, I didn't ask). So it sounds like a fairly intense process? It came back perfect, never had another issue with it.
Hopefully my dealer will come to the conclusion that the system needs to be re-calibrated. Thanks!
11-16-2018, 03:18 PM
#12
Drifting
The dealer I bought my CTT from was the same dealer that sold it new, and serviced it since day one. During my pre-purchase test drive one day a warning message started flashing up on the MFD that the ACC system was being disabled and was not operational (I don't recall the exact message and symbol). You could not enable it after that, and then sometimes it would just come back online momentarily, only to get the error message again shortly after. When I informed the dealer their in-shop diagnosis indicated the system was out of specs. The dealer then found out through the original owner that he had hit a piece of tire thrown up by another vehicle on the highway. This apparently impacted the 'eye' enough to require calibration. Once they did that, I never had another issue with it.