Consultants say interference in vehicle electronics is possible

dr_jeff wrote: snip

But checking out someone else's code is a real bitch. Several times I was given someone else's code to use as a starting point for a similar program. I usually ended up throwing it away and doing my own from scratch because I was convinced it would take less time.

Reverse engineering is never easier than forward engineering. It depends too on how well project management enforces documentation rules/guidelines.

Even so, one problem is that once you understand someone else's code well enough, you can get trapped into thinking like them, and overlook that surprise condition that the original coder overlooked :-(

Reply to
Don Stauffer
Loading thread data ...

Toyota may, but the NHTSA sadly does not. On the other hand, they may be able to call in some folks from the NTSB, for example, who do.

It's a lot easier to find odd conditions with code reviews and verification than with exhaustive testing. But it's also very, very expensive.

--scott

Reply to
Scott Dorsey

In this case, I doubt it. In my opinion, the fault (if one exists) is much more likely with the electronic hardware platform than with the software running on it. You can test the code all you want, but it won't be until that 'race condition' or similar problem is found in the hardware that the engineers can even begin to understand why the process doesn't act as expected.

Reply to
Obveeus
15 yr ago I read of 1 car in USA using auto cruise control drtve past a truck using CB radio, this car @ once got unintended acceleration, this driver switched off his auto cruise & ended this problem. He told medias to warn users of auto cruise control against CB radios.
Reply to
TE Cheah

Maybe fifteen years ago, but EMI suppression has advanced since then in the automotive industry and many other industries too.

Reply to
dbu''

There was ONE model of cruise control I heard about that was extra-fussy about CB Radio interference and IIRC it was OK with a 4 watt unit installed in the vehicle, but a 100 watt Linear amp in a vehicle within a couple hundred feet could "jam" it.

Those cruise control units were VERY primitive compared to anything on the market today. The affected unit was made by ARA if I remember correctly and the problem only occurred if using the engine speed sensor option instead of the magnets on the driveshaft - and that was closer to 20 or 25 years ago (very early 1980s - early Chevy Citation comes to mind.

Reply to
clare

It's not just cruise control... there are a huge number of trucks out on the road that are violating the FCC emission regulations by three orders of magnitude. Consequently anything that isn't very carefully shielded with proper grounding design can have serious problems.

--scott

Reply to
Scott Dorsey

But if this was the real issue it would be much more easily detected and repeatable.

Reply to
Obveeus

Cruise control usually used vehicle speed rather than engine speed. If the car kicks in a lower gear (e.g., when going up hill), then the car would slow down to keep the engine speed constant.

I am not saying that there weren't any cars that used engine speed rather than vehicle speed, but I would think that there are few.

Jeff

Reply to
dr_jeff

Wow! People are using CB radios with 12,000 W of power. That would require a 1000 AMP alternator just for the radio (12 V x 1000 A = 12,000 W). Note: the FCC limit is 12 W and 3 orders of magnitude is 1000 (10 x

10 x 10).

Jeff

Reply to
dr_jeff

I wasn't addressing the reality of such a CB setup. I was addressing the larger implication of any external signal (CB, overhead power line, 'noise' from a failing alternator on a passing car, the Whimshurst static machine at the local highschool, etc...) effecting the Toyota electronics. While 'sun spots' might be random and unrepeatable events (though I doubt focused/isolated to 'aim' at only one vehicle) the rest of these external signal events are likely to be traceable/repeatable. Even beyond being repeatable/traceable, I would guess that Toyota has tested for such extreme external forces; if not before the product was ever released, then certainly by now with all the bad press.

I still think that it (if there is a real problem) is far more likely to be an internal electronic issue that puts the computer controls into an unstable/unknown state.

Reply to
Obveeus

Go here to read about the FCC rules which might apply to the situation you mentioned. I don't believe there is such a rule regarding "three orders of magnitude"

Check back when you find it and cite the paragraph so that I can learn too.

Cheers and good luck

Reply to
dbu''

Every car I have owned, starting with the 1960 Chrysler Imperial, has been equiped with cruise control. They are/were all designed to regulate vehicle speed, not engine speed. I can't remember any instance of a system that attempted to regulate engine speed, though I do remember some aftermarket kits in the 60's & 70's that were simple mechanical throttle controls.

Reply to
E. Meyer

No one was claiming any factory cruise control worked by keeping engine speed fixed. Aftermarket cruise controls had that option though, and for cars with standard transmission it was a reasonable choice to tap off the coil signal rather than affix magnets to the driveshaft. The only down- side was if you set the cruise to 60 in 5th gear, and resumed in 4th you'd be doing 70 or so, depending on gear ratios.

Reply to
Mark Olson

All the aftermarket kits (as well as factory add-on kits) I encountered for manual shift cars all passed the speedometer cable through the unit for speed sensing and added a second cut off to the clutch pedal (along with the brake pedal cut off present on automatic trans units).

Reply to
E. Meyer

I installed two kits such as I described in 1981 Dodge Colts, I can't remember the brand name, they had the option of putting magnets on the driveshaft (axle shaft in a FWD car) or picking the signal off the coil. I've also installed an Audiovox CCS-100 cruise control in a motorcycle, and it has the option of picking the speed signal off the coil or fitting a magnetic pickup to a driveshaft (not on a motorcycle obviously).

installed a similar kit in a motorcycle

Reply to
Mark Olson

You're about 15 years newer than my generation. I guess it all depends on when you did it.

The most exciting ones were the Perfect Circle units in use in the 60's. The '60 Imperial and the '63 Olds both had the same unit. Mechanical throttle linkage & electronic servo, none of this wimpy vacuum stuff.

Every once in a while it would have a brain fart and just slam the pedal to the floor. If you could get the edge of your shoe under it you could pull it back, but you had to be quick & since both of those cars had huge V8's, the other foot would be immediately firmly planted on the crappy drum brakes.

Just to make it more fun, the cruise didn't have to be engaged for this "feature" to work. Definitely added a degree of excitement to driving. Reports of little old ladies plowing through the back of their garages prompted the first round of fail-safes and controls on these things.

As far as I know now, the cruise functionality is handled by the ECM on pretty much all new cars, which leads us right back to software.

Reply to
E. Meyer

Yup. And because it's a serious and well-known issue, just about all cars sold in the US go through aggressive EMI testing. If only they would test other consumer products as well.

Toyota is actually better about that than most manufacturers, although they issue a whole lot of warnings about not installing high power radio equipment in their cars and they won't provide support if you do. Contrast that with Ford, which has a whole support organization to help folks putting high power radio gear into fleet vehicles (mostly due to the police market).

--scott

Reply to
Scott Dorsey

Nope, FCC limit is FOUR watts.

And I have sadly seen Alabama Pillboxes in the 6KW range. Really nasty output waveform too. And yes, they require a seperate alternator and aren't normally run off a 12V system.

--scott

Reply to
Scott Dorsey

Hams (amateur radio operators) can legally run 1500 watts in the US. And many do so using homebrew mobile installations. At this power level if the installation is not done correctly the car electronics can not only malfunction but be damaged.

But RF can be unpredictable and cause problems at low power also. I have had my cruise control affected with as little as 5 watts when using a VHF or UHF frequency (144, 220 or 440 MHz). Rerouting of cables and/or better grounding usually fixed it.

Reply to
AJL

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.