Adaptive cruise control

Rapid Roger · #1 (**permalink**) 04-05-08, 08:09 PM

Anyone have "Adapitve Cruise Control" on an 08 DTS.Mine works off and on and my dealer is having a terrible time pinpointing the problem.At first they thought it was the aftermarket grill but we have pretty much eliminated that.

Sometimes it will work perfectly and other times I have to intervene and apply the brakes.Has anyone else had problems with this unit.....?If so...Please post the details......Thanks
Roger

Superjim · #2 (**permalink**) 04-06-08, 08:57 AM

Roger,

I assume you have varied the distance settings for the cruise.
Six car lengths.. seven car lengths etc etc.

The RATE OF CLOSURE may have something to do with it also in conjuction with the distance gap you have set.

Texas Jim

ewill3rd · #3 (**permalink**) 04-06-08, 05:46 PM

Have they tried re-aiming the cruise unit?
It could be looking in the wrong spot.

Rapid Roger · #4 (**permalink**) 04-06-08, 07:38 PM

Quote:

Originally Posted by ewill3rd

Have they tried re-aiming the cruise unit?
It could be looking in the wrong spot.

Thanks for your input.Yes....I believe they have tried to re-aim it.I know they want to blame it on the E&G aftermarket grill I have installed and in my talks with E&G they indicate they have not had a reported problem.Your thoughts have merit because it sometimes picks up(The little car icon lights up) cars passing on the left.

Fortunatly I have an excellent dealer and I know they will get to the bottom of this but I am tired of driving a different car every week while they have it.

ewill3rd · #5 (**permalink**) 04-07-08, 07:25 AM

I know most guys are not familiar with the aiming procedure... and quite frankly it is a pain in the hind quarters.
I would almost be willing to bet that this is an aim issue.

nosro · #6 (**permalink**) 04-07-08, 02:19 PM

I do not know your particular situation, but aiming is absolutely crucial on these type of radar/vision systems. You probably have no idea how much engineering work goes into locating these thing (from a design standpoint) and then correcting aiming them on the assembly line.

I would not rule out the E&G grill causing a problem. I know E&G will assert that their grill has no effect, but I am also willing to bet that they did nothing more than drive 1 car around with the grill on. I highly doubt they actually commissioned a re-validation of the radar system. Remember that the stock grill is essentially plastic while the E&G grill is metal - that alone could cause a problem. (Although a hole may be cut out for the radar unit, the proximity of metal around the hole could result in diffraction effects.)

If the radar is failing to pick up a car 20 feet and straight ahead in front of you, I would experiment with putting the old grill back on to truly eliminate the grill as a cause - that's the only way to experimentally prove the E&G grill is not at fault.

ewill3rd · #7 (**permalink**) 04-07-08, 05:09 PM

^^^^^^^^good advice there.

Rapid Roger · #8 (**permalink**) 04-07-08, 06:21 PM

Thanks for the replies.As of now,the grill is the prime suspect.I will be dropping the car off at my dealer tomorrow and the first action will be to reinstall the stock grill.If this corrects the problem I guess I have a problem with E&G.

ewill3rd · #9 (**permalink**) 04-07-08, 10:04 PM

Our window tint guy did a back glass on a DTS, after that the reception was awful.
I exhausted every avenue of diagnosis and finally asked him to remove the tint just to eliminate it as a cause.
He insisted that there was no way the tint could interfere but he agreed and let me know that we'd be paying twice if it didn't fix it.
It did, he was man enough to admit he was mistaken and went back to his supplier with a complaint.

Sometimes it is easy to check one car and assume it is not a problem.
A test field of 1 hardly cuts it.
Let us know if you still have issues with the stock grille.

Rapid Roger · #10 (**permalink**) 04-11-08, 07:57 PM

Update.......My dealer has had the car since I last posted.They have eliminated the grill as the source of the problem.They just recieved a DTS with this option and it performed just as poorly as mine.....They are stumped and have initiated communication with the GM tech center.

If anyone has this option and it works to your satisfaction I would appreciate an email so we can discuss it in detail.Thanks
Roger

nosro · #11 (**permalink**) 04-11-08, 10:37 PM

Rapid Roger - can you describe your complaint in greater detail? Is the problem that it once worked well and now it works poorly or that it has always worked poorly? I originally thought it was the former.

If it is the latter, that it has always worked poorly, and the performance appears to be the same as another new vehicle, then the short answer is: that's what you get for being on the bleeding edge. Adaptive cruise systems such as this are very much imperfect. It is not just GM products. If you ever get the chance, test drive a Jaguar or a Mercedes with one of these systems. Jaguar is in fact even worse. My experience with a Mercedes S-class over several days also demonstrated a "hit or miss" performance. In fact, my experience with the S-class led me to swear off such systems completely for the next few years - it's disconcerting the one time out of ten it fails to work.

This is the nature of the beast. These things are very much state-of-the-art and you can expect a lot of teething pains to go along with these systems.

I hope this is not a case of high expectations - I know how lousy that can feel.

Rapid Roger · #12 (**permalink**) 04-11-08, 11:49 PM

Quote:

Originally Posted by nosro

Rapid Roger - can you describe your complaint in greater detail? Is the problem that it once worked well and now it works poorly or that it has always worked poorly? I originally thought it was the former.

If it is the latter, that it has always worked poorly, and the performance appears to be the same as another new vehicle, then the short answer is: that's what you get for being on the bleeding edge. Adaptive cruise systems such as this are very much imperfect. It is not just GM products. If you ever get the chance, test drive a Jaguar or a Mercedes with one of these systems. Jaguar is in fact even worse. My experience with a Mercedes S-class over several days also demonstrated a "hit or miss" performance. In fact, my experience with the S-class led me to swear off such systems completely for the next few years - it's disconcerting the one time out of ten it fails to work.

This is the nature of the beast. These things are very much state-of-the-art and you can expect a lot of teething pains to go along with these systems.

I hope this is not a case of high expectations - I know how lousy that can feel.

Nosro....It works intermittantly......I drove a lexus with this system and it worked perfectly.In my case it may or may not see a car in front(A light lights when it sees a car) if it does not see the car it will not apply the brakes or speed up as necessary.

My dealer agrees that there is a problem with my car and another new car we test drove.I can see no reason why it should not work as well as that on the Lexus............

nosro · #13 (**permalink**) 04-12-08, 01:41 AM

Quote:

Originally Posted by Rapid Roger

...

My dealer agrees that there is a problem with my car and another new car we test drove.I can see no reason why it should not work as well as that on the Lexus............

I wish the press could understand how incredibly complicated these systems are. These are not just "stupid" radar guns pointed ahead. There is an incredible amount of signal processing that has to occur just to differentiate between a truck and a manhole cover or to differentiate between the car immediately ahead of you or an oncoming car in an opposing lane.

What you say is equivalent to saying "I see no reason why Anti-lock brakes on a Chevrolet can't be as good as that on a Mercedes" in 1990 when ABS was still state-of-the-art technology. There were vast differences among different ABS systems. Today, with 15 years of experience, it is true that ABS is now similar in performance on all cars.

As I said, if you want an eye-opener, try a Jaguar. The Lexus is OK, but if you spend as much time in it as you have in your DTS, I have no doubt you would have similar complaints.

I hate to be the bringer of discouragement, but I highly doubt you will find anything wrong or get any improvement, especially if another new DTS behaves the same way. It is simply the nature of these first-generation systems (or any first-generation system of any new technology).

mack1a · #14 (**permalink**) 04-12-08, 02:13 AM

Funny, my 2006 DTS Perf Level still has the ACC problem I posted here a long time ago.

It fails in the sense that it occasionally sees a phantom vehicle right in front of the car, sounds the alarm and does hard braking (well as hard as ACC braking can be).

The failure is very intermittent and it will fail with absolutely no reflect object anywhere in front of the car. The common element is that there is always a police car in the vicinity. Of course the police say there is no way, they can cause this.

The dealer suspected alignment and it checked out to be good. I strongly suspected it was good as I can drive thru a toll booth and the car never picks it up.

Anyway, the failure is still there (fails once per month or so). The NTSB never reacted to my input and I am not going to spend time trying to teach a pig to sing.

I always just hit the off button when it fails and keep from disrupting traffic by coming to an abrupt and unanticipated stop.

Overall, I really like the feature and I understand this ones unique frailities.

nosro · #15 (**permalink**) 04-12-08, 10:43 PM

Quote:

Originally Posted by mack1a

...

It fails in the sense that it occasionally sees a phantom vehicle right in front of the car, sounds the alarm and does hard braking (well as hard as ACC braking can be).

The failure is very intermittent and it will fail with absolutely no reflect object anywhere in front of the car. ...

This is very common in these first-generation systems (not just Cadillac). This is not a "failure" in the sense that there is nothing broken and everything is working as designed. There will be no trouble codes found.

These first-generation systems work on a very probabilistic basis. That is, for situations involving a certain amount of traffic, it generates false-positives (brakes when not required) "X" percent of the time and it generate false-negatives (does not brake when required) "Y" percent of the time due to situation-to-situation variations.

As these systems mature, "X" and "Y" should decrease. But be clear - it probably will not go to zero within the next two decades. (Think of it this way - even though anti-lock brakes have been around for almost two decades, there are still cases of "X" and "Y" errors.)