PCS Lag
12-13-13, 10:58 PM
#1
Intermediate
Thread Starter
PCS Lag
I'm not sure did this happen to anyone before, for those have PCS in their car please be ware, it happen to me yesterday, the system have some lag which could cause rear end accident.
I was driving around 40-45 mph on the road, and the car in front of me start slowing down, the PCS start beeping telling me to brake; however, since the next lane have to car, I move to it instead without touching the brake.
The car then command a emergency stop after I moved to the empty lane, which will not respond to my full throttle input until the speed slow down to nearly stop.
It happen again when I switch to another lane minute later and almost cause the SUV rear ended me.
Brought back to the dealer try to duplicated the situation today, but no luck cause it is really dangerous to make it happen again.
According to the manual about the PCS, it is design to slow down the car to a slow enough speed when detect collusion in front of the car, which will not stop the car completely.
After the drive we discussed and come up with an explanation:
Once the PCS detect a collusion is inevitable and command the brakes to do an emergency stop; the car will not respond to any throttle input until the car had slow down to a preset speed, it will complete the full braking process regardless of even there is no obstacle in front.
This only happen during traffic in town (especially Spring Mountain Rd in Las Vegas, people tend to drive extremely slow on that road for unknown reason, you will know if you live here) the system will have a bit delay before braking and it is not design to scan the road again to override the process, so it will brake after you move to an empty lane.
They said I can try to tap the brake really quick to let the system know I am aware of the obstacle in front to override the process; however, I didn't encounter this again, so haven't find out yet.
Another way may stop the braking could be sharp steering input, but since I'm just moving to next lane it didn't apply to me that day.
So if anyone out there have the PCS install and usually cutting lane very quick and close to cars in front, this could happen and may end up on a tow truck. It will be better to turn it off in city if driving in that style.
If someone know tapping the brake or sharp steering can disengage the stopping please let me know.
My dealer said I can take the car back if it happen again and they may be able to download some data from the car, but make sure don't turn the car off cause it will reset all the data.
I was driving around 40-45 mph on the road, and the car in front of me start slowing down, the PCS start beeping telling me to brake; however, since the next lane have to car, I move to it instead without touching the brake.
The car then command a emergency stop after I moved to the empty lane, which will not respond to my full throttle input until the speed slow down to nearly stop.
It happen again when I switch to another lane minute later and almost cause the SUV rear ended me.
Brought back to the dealer try to duplicated the situation today, but no luck cause it is really dangerous to make it happen again.
According to the manual about the PCS, it is design to slow down the car to a slow enough speed when detect collusion in front of the car, which will not stop the car completely.
After the drive we discussed and come up with an explanation:
Once the PCS detect a collusion is inevitable and command the brakes to do an emergency stop; the car will not respond to any throttle input until the car had slow down to a preset speed, it will complete the full braking process regardless of even there is no obstacle in front.
This only happen during traffic in town (especially Spring Mountain Rd in Las Vegas, people tend to drive extremely slow on that road for unknown reason, you will know if you live here) the system will have a bit delay before braking and it is not design to scan the road again to override the process, so it will brake after you move to an empty lane.
They said I can try to tap the brake really quick to let the system know I am aware of the obstacle in front to override the process; however, I didn't encounter this again, so haven't find out yet.
Another way may stop the braking could be sharp steering input, but since I'm just moving to next lane it didn't apply to me that day.
So if anyone out there have the PCS install and usually cutting lane very quick and close to cars in front, this could happen and may end up on a tow truck. It will be better to turn it off in city if driving in that style.
If someone know tapping the brake or sharp steering can disengage the stopping please let me know.
My dealer said I can take the car back if it happen again and they may be able to download some data from the car, but make sure don't turn the car off cause it will reset all the data.
12-15-13, 01:00 AM
#4
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Interesting. Thank god you and other passengers are safe. I had similar situations with my 2014 Mercedes E350. But it was beeping then I hit the brake quick once then the system disengage it's emergency action. I believe Mercedes pre collision system too intelligent than Lexus in this area
12-15-13, 04:17 PM
#5
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Glad to hear that this didn't result in anyone being in an accident. These PCS reports are pretty worrying though; it's just a huge incident/lawsuit waiting to happen.
Stay safe and keep us posted if Lexus does anything about it. I'm glad I didn't spring for this option, but at least it sounds like you can disable it if you do have it. This also makes me think that Lexus doesn't have a full stop-and-go dynamic cruise control for some serious safety reasons, unlike some of their competitors.
Stay safe and keep us posted if Lexus does anything about it. I'm glad I didn't spring for this option, but at least it sounds like you can disable it if you do have it. This also makes me think that Lexus doesn't have a full stop-and-go dynamic cruise control for some serious safety reasons, unlike some of their competitors.
12-15-13, 08:18 PM
#6
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Pushing and holding the trac off will disengage pcs as well. In case you are at the track. Mine has PCS but I haven't ran into that situation yet. Thanks for the heads up!
12-16-13, 02:11 PM
#7
Intermediate
Thread Starter
Interesting. Thank god you and other passengers are safe. I had similar situations with my 2014 Mercedes E350. But it was beeping then I hit the brake quick once then the system disengage it's emergency action. I believe Mercedes pre collision system too intelligent than Lexus in this area
I'm sure the people behind me thought I was doing it in purpose or so...
I think what the system should do is continue scanning the road and there is no need for full stopping process if there is nothing in front and respond to the throttle quicker.
May be the Mer system is better since they have more experience on these kind of stuff LOL
Really want to get the new 2015 C63 AMG
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01-29-14, 02:21 AM
#8
its happened to me twice , First one , a Mitsubishi lancer was about to hit from back because i did the same The car in front me start to slow down to take a U-Turn and I changed the lane fast then PCS start working and it engage the full break 
.. Second , I was driving 140km on highway and I pushed the throttle to pass the car in front of me and its start working ! i hate this I can't drive aggressively with this car .. I will turn it off today .
.. Second , I was driving 140km on highway and I pushed the throttle to pass the car in front of me and its start working ! i hate this I can't drive aggressively with this car .. I will turn it off today .
01-29-14, 03:53 AM
#9
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This had happen to me two times as well, once i was cutting into an open lane like the OP said. It flashed "BRAKE!" and then it was cancelled a second later... and another time i was driving on a wide open road with no cars in front, and it flashed brake! for a very brief moment...
01-30-14, 08:16 AM
#11
I'm not sure did this happen to anyone before, for those have PCS in their car please be ware, it happen to me yesterday, the system have some lag which could cause rear end accident.
I was driving around 40-45 mph on the road, and the car in front of me start slowing down, the PCS start beeping telling me to brake; however, since the next lane have to car, I move to it instead without touching the brake.
The car then command a emergency stop after I moved to the empty lane, which will not respond to my full throttle input until the speed slow down to nearly stop.
It happen again when I switch to another lane minute later and almost cause the SUV rear ended me.
Brought back to the dealer try to duplicated the situation today, but no luck cause it is really dangerous to make it happen again.
According to the manual about the PCS, it is design to slow down the car to a slow enough speed when detect collusion in front of the car, which will not stop the car completely.
After the drive we discussed and come up with an explanation:
Once the PCS detect a collusion is inevitable and command the brakes to do an emergency stop; the car will not respond to any throttle input until the car had slow down to a preset speed, it will complete the full braking process regardless of even there is no obstacle in front.
This only happen during traffic in town (especially Spring Mountain Rd in Las Vegas, people tend to drive extremely slow on that road for unknown reason, you will know if you live here) the system will have a bit delay before braking and it is not design to scan the road again to override the process, so it will brake after you move to an empty lane.
They said I can try to tap the brake really quick to let the system know I am aware of the obstacle in front to override the process; however, I didn't encounter this again, so haven't find out yet.
Another way may stop the braking could be sharp steering input, but since I'm just moving to next lane it didn't apply to me that day.
So if anyone out there have the PCS install and usually cutting lane very quick and close to cars in front, this could happen and may end up on a tow truck. It will be better to turn it off in city if driving in that style.
If someone know tapping the brake or sharp steering can disengage the stopping please let me know.
My dealer said I can take the car back if it happen again and they may be able to download some data from the car, but make sure don't turn the car off cause it will reset all the data.
I was driving around 40-45 mph on the road, and the car in front of me start slowing down, the PCS start beeping telling me to brake; however, since the next lane have to car, I move to it instead without touching the brake.
The car then command a emergency stop after I moved to the empty lane, which will not respond to my full throttle input until the speed slow down to nearly stop.
It happen again when I switch to another lane minute later and almost cause the SUV rear ended me.
Brought back to the dealer try to duplicated the situation today, but no luck cause it is really dangerous to make it happen again.
According to the manual about the PCS, it is design to slow down the car to a slow enough speed when detect collusion in front of the car, which will not stop the car completely.
After the drive we discussed and come up with an explanation:
Once the PCS detect a collusion is inevitable and command the brakes to do an emergency stop; the car will not respond to any throttle input until the car had slow down to a preset speed, it will complete the full braking process regardless of even there is no obstacle in front.
This only happen during traffic in town (especially Spring Mountain Rd in Las Vegas, people tend to drive extremely slow on that road for unknown reason, you will know if you live here) the system will have a bit delay before braking and it is not design to scan the road again to override the process, so it will brake after you move to an empty lane.
They said I can try to tap the brake really quick to let the system know I am aware of the obstacle in front to override the process; however, I didn't encounter this again, so haven't find out yet.
Another way may stop the braking could be sharp steering input, but since I'm just moving to next lane it didn't apply to me that day.
So if anyone out there have the PCS install and usually cutting lane very quick and close to cars in front, this could happen and may end up on a tow truck. It will be better to turn it off in city if driving in that style.
If someone know tapping the brake or sharp steering can disengage the stopping please let me know.
My dealer said I can take the car back if it happen again and they may be able to download some data from the car, but make sure don't turn the car off cause it will reset all the data.
12-28-14, 12:54 PM
#13
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I have an ES350. I've noticed my PCS engages only when I'm in Cruise mode. I'm not sure if I would get an audible warning if I got too close to a vehicle and not in cruise mode. I've never tried it. I'm afraid I might rear-end the car in front of me. Also, the on/off button on my 2013 ES350 is behind the glove compartment door on the right side - only in Canada Eh!
12-01-15, 12:55 AM
#14
Intermediate
Thread Starter
The quick solution will be quickly tap the brake a bit when you heard the PCS warning flashing, that will disable it, if not it will take few second before the system allow you to speed up again, which means the person behind you will be screaming 
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