DRCC Freezing

We’ve been running into a problem with the DRCC on our 2011 Model 5. In simple terms, the DRCC freezes – locking onto car in front and activating the beeper/hitting the breaks – even when no vehicle is ahead! So far, this has happened once to my wife (when she was making a 90 mile trip) and 3 times this weekend on a trip from Rochester, NY to St. Paul, MN.

In all cases this has occurred as the car was passing a semi, when the front of the car was even with the semi’s drivers door. In one case, there was no car in front – just acted like there was one. Whenever this occurs, the car continues to brake and the only immediate solution is to turn off the Radar. Also when we re-engage the DRCC, the unit is still frozen – braking for a non existent vehicle. No problems turning the DRCC off and using the ordinary cruse. What seemed to “clear” the condition was pulling off the Interstate and turning off the car. I also noted that (after it had froze again) that when the ambient temperature had dropped below 90 degrees that the DRCC cleared. The first time my wife ran into this was hot too.

In summery, this has happened only when:

• · Passing a semi
• · Temperature is high (above 90).

I don’t believe that it is an alignment issue, as I’ve been amazed at how narrow the radar pattern seems to be (and very nicely tracks the steering).

Right now, we are in St. Paul for a week – so taking it to the dealer will have to wait a bit.

I did a search here on “DRCC Malfunction”, “DRCC Problem” and “DRCC Freeze” but didn’t find a problem like mine (with the unit freezing).

Any suggestions/comments?

 

Update;

First, let me clarify my earlier post above. DRCC is part of the Advanced Technology Package that is a option on the Model 5 Gen III Prius (it was my primary reason to purchase the Model 5). It is Toyota's Brand Name for Adaptive Cruse Control. Basically, when using cruse control, it will automatically track any vehicle in front of your vehicle and will switch the cruse control to a constant distance mode to maintain a safe distance (which you have control over) from the vehicle ahead. If the distance gets too short (or when another vehicle suddenly pops in front of you), it will rapidly decellerate and .flash/sound a warning. In my case it would act as if another vehicle was 10 feet away - even when there is no vehicle at all. This creates a dangerous situation when you are traveling an Interstate at 75mph, passing a Semi and with someone tailgating you (expecting you to finish passing the Semi).

I've contacted both my dealer and Toyota over this. They will do nothing as the dealer was not able to observe the condition (it happens intermittently under limited conditions). The dealer found that no codes were thrown by the DRCC system - so, without those codes, there is nothing they can do. Of course, both the dealer & Toyota loose track of the fact that the system must be programmed to recognize specific malfunctions and to THEN generate an appropriate code! It appears that the system ACTUALLY THINKS that there IS a vehicle in front that this is an entirely NORMAL operation.

This is the typical HEAD BURIED IN THE SAND problem that has got Toyota in trouble before!

 

The lens was clean (first thing I checked when it happened). It was a bright sunny day when this happened. Also no error codes (just acted like there was a car in front). I have had "normal" problems with the DRCC in the winter where the lens is covered with ICE. I have also found that when it is raining that water thrown up by a car in front can make that car invisible to the radar with no error codes.

 

Exactly. Without the code Toyota will do nothing!

No, because it performed normally after shutting the car down - at least it performed fine till the problem re-occurred an hour later.

I wouldn't want them to do that as normally the alignment seems perfect. I doubt that the dealer can do as well. It is pretty clear to me that the problem is some sort of interference from the Interstate trucks that we were passing.

That is our plan. HOWEVER, every time that this has occurred we have been on a long trip so we can't take it to our dealer. When it occurs we will have to locate a dealer, convince them to look at it (which could be a battle in itself), and make it to our night's destination.

My real point is that Toyota treats potentially serious problems like this as an annoyance. A logical approach would be for them to swap out the radar unit and check it out under high temperature conditions. But they would rather just ignore potential safety issues.

 

The likely "cause" IS an RF emission from the truck. The DRCC should (and probably is) designed to filter out such emissions. However, if there is a cold solder joint or an IC with impurities, the unit can FAIL to perform as designed (and still not throw error codes). (I have an electronic engineering background including complex circuit board manufacturing experience).

I did call Toyota Customer Car several times about this. Unless it throws a code, or the dealer observes the failure (meaning that it has to be locked up when they look at it) they won't do anything.

Stepping on the BRAKE (not the GAS) disengages the DRCC - BUT if someone is tailgating me this failure can result in a collission (Imagine cruising down I70 at 75mph, truck ahead going 5mph slower, pull out to pass before DRCC captures the truck, no car ahead in the passing lane, meantime, another car doing 78 approaches me and follows a bit too close in the passing lane. He expects me to pass the truck and pull back into the right land and he will continue on his merry way - when SUDDENLY, for no apparent reason, my car SLAMS ON THE BRAKES!!!!!

I am in the process of reporting this to the NHTSA.

 

That's the plan (besides filing with the NHTSA).

 

UPDATE:
Last night I filed with the NHTSA. You can see my filing here (put my ODI record number: 10471467 in the search box. I also found two other DRCC complaints. One is similar to mine (involves semi tractor trailors). It is ODI number: 10448415.

 

My problem was quite a bit different than yours. But the fact that both the dealer & Toyota want to ignore these problems is no different.

In my case it was strictly a DRCC problem - not a PCS problem (though there are common components in the system). Mine only occurred when passing an Interstate Semi and when that happened the DRCC system locked up (system kept "seeing" a vehicle in front - when there was none). Last, it only occurred when the temperature was high (around 90).

We haven't had the problem since last August, but we haven't driven it much in hot weather either (living in Western New York). Other than this issue I have been very happy with the DRCC. I've particularly been impressed with how accurately the radar is aimed (can easily observe that the beam is aimed by observing the display as I change lanes to pass a vehicle).

 

• First, what Toyota is it that uses a laser for Adaptive Cruise Control? I suspect that it uses Radar too.
• Second, I find that the effective beam angle of my system to be pretty narrow.
• Third, I am well aware how to turn off the DRCC and use just the normal cruse control. I am not a "dolt". However, I paid a lot of money for this feature and, as I indicated in my most recent post, I like it. When the DRCC did Freeze, I did turn off the DRCC and when later I turned the DRCC back on it was still frozen. Only shutting the car down, or in one case, when we drove into cooler temperatures, did it release.
• Lastly, if trucks have all these gadgets and are emitting signals, then the DRCC system should be designed to block those out. Having an electronics & electronics manufacturing background, I suspect that the DRCC does have circuitry to block these and (as I said in my original post) that there is likely a cold solder joint that acts up when it is hot that is causing that filter to fail (and causing my DRCC to see a "phantom" vehicle).

What frustrates me is Toyota's lack of concern. It is this type of "Head Buried in the Sand" attitude that has got them into trouble before.