Radar Controlled Cruise Control Malfunction

I was cruising along yesterday and my cruise shut off telling me the radar assisted cruise control was no longer available. I tried to reengage it a few times and no luck. Pulled over and rebooted the truck and nothing still no luck. Then when sitting in the drive through at Sonic, I wondered if something was on the grill. I got out, wiped my hand across it and cleaned off - a gnat carcass. Maybe some Arizona dust too? Didn't really see anything. But apparently rubbing the Toyota emblem works like rubbing the Buddha-Belly and it restored my radar controlled cruise control.

Was it the almost imperceptible fine layer of dust? Could a gnats ass cause me that much of an issue? How do people in the South East like Texas to Florida and up to South Carolina live with this? Y'all have some BIG Juicy Bugs.

 

I've had the radar cruise go unavailable on me twice in two years. Both times it was in a heavy south Florida downpour, and both times it came back on it's own in less than 5 min. Other than that have never had an issue, even here in bug land

 

I have lost cruise in my old RAV 4 and my Taco because the sensor was muddy from overspray in the rain.

 

How’s the windshield? Any cracks or dirt obscuring the camera sensor behind the rear view mirror?

 

Good question. Should be clean and clear. Truck has 200 miles on it but I'll go check.

 

Window is crystal clean and clear. Nothing on it.

 

I wonder if it could be a faulty radar sensor from factory? Never heard of that happening, but if it becomes more of a common thing then could be worth documenting for the dealership for eventual replacement? Mine has only shut off on me in heavy snow/rain.

 

I have a 22 TRD Sport that I got in July of last year. It has less than 10k miles on it. I took my first long trip in it this weekend. 450 miles each way. Cruise control worked fine on the way there. But in the last hour on the way home, every time I needed to slow, whether I hit the brakes and then hit resume, or whether the radar slowed it then sped up again it would always go back to one mph slower than I had it set. For example, if the cruise was set at 75, it would resume to 74, but still say it was set at 75. Got me kind of baffled. Would love to hear input from some of the folks here that know more than me. Thanks.

 

My understanding the camera in the windshield has nothing to do with the cruise control. Only the Radar in the grill.

 

PCS, LDA and Dynamic radar cruise all use both sensors. If you obstruct the camera sensor or crack your windshield in front of it none of them will work.

In the owners manual, 4-5 Using the driving support systems under dynamic radar cruise control:
Situations unsuitable for dynamic radar cruise control
…
• When there is rain, snow, etc., on the front surface of the radar sensor or camera sensor
…
When the sensor may not be correctly detecting the vehicle ahead
Pictures show a car using both sensors to detect vehicles in front of it

 

If I remember I'll put tape over the camera tomorrow and test; I invite you to do the same. The camera I believe is only to detect non-speed related roadside problems and to turn OFF cruise control when one may be detected. The camera cannot see through fog, only the Radar can ...somewhat. I would like to see something other than the Owner's Manual such as a technical explanation of the cruise controls operation to delve into. I've put the tape on my dash for tomorrow's test.

 

Your probably gonna have to drive it more than 200 miles to figure it out.

 

The manual is usually sufficient for me. If you have two sensors capable of detecting objects in front of the vehicle why would you only rely on one for a feature that is used at highway speeds? If human eyes can see taillights in inclement weather I’m sure the camera sensor can use them as a second point of reference along with the radar

 

How does the radar know when the object (vehicle) in front of you has moved into a different lane? Or when you move into a different lane? The radar does not sweep like your typical radar does. The radar relies on what the camera sees.

 

My testing revealed the camera is indeed not necessary for the Adaptive Cruise Control to function, however Toyota has made that point moot in their programing. The cruise control seems to operate off the front grill radar sensor for a period of time or distance, future testing would be necessary to determine if it is a time or distance function. I would say it was no more than 3 miles or three minutes. For continued use of the adaptive cruise control the camera is indeed necessary per Toyota's desires.

My testing went as follows: Engine off on a highway on ramp, covered the windshield camera with tape. Started engine and entered traffic on a multilane highway, activated adaptive cruise control at a higher speed than the traffic in the slow lane, my vehicle pulled up behind the vehicle in front of me and slowed down just like it should; I pulled my vehicle over to the left into a lane with no traffic and my vehicle accelerated up to my set cruise speed passing the vehicle it previously slowed down for. Then after the approximately 3 miles things went kilter with a center display of the Camera unavailable and the Collision Avoidance light lit up.

I would still like to see a detailed theory of operation description to learn just what collusion there is between the adaptive cruise control and the collision avoidance? I had previously thought they were the same.

My ignorant guess as to how the radar is working is with multiple "Beams" of some sort. Just what the camera does is still not readily apparent.

Oh, I thought I detected that when the camera is covered with tape the regular speed-based cruise control does not work either, however this was not crystal clear. I believe I have encountered the speed-based cruise control not working either with ice on the grill and with the grill removed.

 

Yes, the radar can tell an object's distance, but without the camera it does not know the bearing in relation to you. This is where the camera comes in. As I stated previously, if you change lanes, the radar doesn't know until the camera tells the truck that the object ahead is is another lane (assuming the lines can be picked up by the camera).

Also, if there was more than one beam, each beam would need to be calibrated (if/when the time comes). It's very rare to see multiple beam radars like that. I have only seen one, used in the military and it's very obvious because you can see each section. This isn't the case for TSS.

 

Sorry, still not understanding. I changed lanes to not have the slow vehicle in front and my vehicle ignored the slow vehicle and speed up. What am I missing?

 

The beam is a narrow cone. It's likely the radar return disappeared at that point. Without an o-scope connected to monitor the return signal, we can't say for sure.

 

Lol that’s a lot of words for “adaptive cruise does use the camera sensor”.
The why and how is inconsequential to wether or not the camera is used, but I understand that you’d like to learn more about the system.
If PCS is disabled radar cruise doesn’t work, nor should it imo.
Despite skewing your testing to prove the point that the system could work without the camera, it doesn’t and that’s all I’m saying

 

You think that was long, I did plenty of other testing, which did not make any sense and I could not put it into words. This is one of those times I am less knowledgeable after the fact than before.