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f1anatic 01-02-2014 08:56 AM

Questions regarding ACC and stationary vehicles
Hey guys,

I have a few questions regarding the behavior of ACC. I have an early 2014, with ACC (but no STOP). I would like to confirm or diagnose the behavior of ACC in my car.

When I enable ACC and set the speed (regardless of whether I have a car in front or not), the car will start detecting moving cars, traveling in the same direction and in my path of travel. There is a set distance of course (4 set distances, I have it set on 4 bars). If traffic ahead of me is slowing down, the car will recognize this (as long as it is within the detection zone) and slow down. Early 2014 Jeeps with ACC slow down to 15 mph then give a warning of ACC being disabled whereas later ones slow down to zero.

Here is my question: what if you have the ACC enabled, set to whatever speed (let's say 35 mph) and the traffic ahead is already stationary (at an intersection) - meaning it does not slow down ahead of you. Will your car recognize this and slow down...whether to 15 mph or zero ? Or will your car stay committed to the same set speed and would eventually cause a collision without driver intervention? This appears to be the case with mine. The collision warning does not come up either.

I can trigger the collision warning if I am on ACC and closing in on the car ahead, also slowing down aggressively in front of me OR if the car ahead is making a left/right turn and I fail to slow down. And yes, it does brake for me.

Please provide the answer for both Early and Late 2014 MY Jeeps with ACC. Please indicate which model you have in your response. Thank you.

SLLJG 01-02-2014 09:45 AM

Re: Questions regarding ACC and stationary vehicles
My 2014 Grand Cherokee, built in April, has version one of ACC. Version 1 does not stop the vehicle. Last summer, Jeep switched to Bosch's new hardware, which does stop the vehicle. Each version has its own unique hardware and software.

I have found version one of ACC to be unreliable, even after upgraded software. Sometimes the EVIC displays "BRAKE!" for no apparent reason. At other times, especially in heavy traffic, ACC is silent.

f1anatic 01-03-2014 09:48 AM

Re: Questions regarding ACC and stationary vehicles
Can anyone else answer my specific question? Thank you.

Aeroguy 01-04-2014 11:56 PM

Re: Questions regarding ACC and stationary vehicles
I have the ACC w/stop and I tried it and it does not appear to be designed to work where it detects a stationary vehicle. I had the FCW annunciate as I approached the stationary vehicle and had to stop the truck. I could not see where the system would be capable of sensing a stationary vehicle ahead and begin the breaking in time to be practical.

2mad2bad 01-05-2014 05:58 AM

ACC with or without stop does not respond to stationary objects (including vehicles). So if your Jeep is set at 35 with a stationary object ahead, it will remain at that speed until the driver intervenes.. All cruise controls work this way.

Spocker 01-05-2014 02:05 PM

Re: Questions regarding ACC and stationary vehicles
I have a '14 GC built in June, and mine will not detect a stationary vehicle stopped in front of the jeep. Current system uses Doppler radar to calculate how fast an object in front of you is moving towards you or away from you, but will 'ignore' stationary objects... If it didn't, your Jeep would constantly be slamming on the brakes and flashing and beeping ' brake, brake, brake' at you!
So to answer your question, your Jeep will stay committed until you impact the stopped car /truck in front of you, unless you intervene. :)

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