Consultants say interference in vehicle electronics is possible

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E. Meyer wrote:


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
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On 3/26/10 9:00 AM, in article 0tGdnS2RIcJqIDHWnZ2dnUVZ snipped-for-privacy@posted.visi,

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.
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wrote:

magnets on the driveshaft instead of tapping into the speedo - and quite a few that used the engine tachometer signal.
I've installed hundreds of them. Likely 50 or more with the engine tach input - and those from at least 3 manufacturers. Compu-Cruise was one, ARA and Dayna I THINK were two others - I know we installed a fair number of each of them.
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I've installed likely hundreds of aftermarket cruise controls - and on front drive vehicles - and particularly with automatic transmissions, there were a LOT that used engine RPM to sense speed.. Compucruise had that option for sure, as did ARA if I remember correctly, and at least one other major manufacturer that I cannot remember right now.. If the transmission downshifted the cruise control immediately shut down, the same as on a standard shift car. ANYTHING that allowed the engine speed to climb quickly disengages the cruise on these units - without requiring a clutch switch if installed on a standard.
I do remember at least one GM X-Car installation that didn't like a HAM radio installation - and another - can't remember what right off hand - that didn't like the old mobile telephone system installation.
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On 3/26/10 2:51 PM, in article snipped-for-privacy@4ax.com,

Boy, that's one sucky setup. Useless from any practical standpoint.

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wrote:

Actually on a standard transmission it worked just great.. On an automatic it wasn't any worse than a lot of today's OEM systems which also "fall out" on a downshift. Only drawback was the "resume" was no good after a shift.

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E. Meyer wrote:

It would work just as well as the setup on my car (a standard), at least until the clutch starts to go. But the cool thing is that my car will maintain the same speed if I upshift and reengage the cruise control (although I why I would want to be in 3rd gear at 65 mph is another question).
Jeff

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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
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wrote:

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

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
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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.
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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
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snipped-for-privacy@panix.com (Scott Dorsey) wrote:

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.
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Absolutely. And presumably hams have the skill required to make sure that they are doing this properly and safely.
K4UMI used to have a 1KW CW rig in his pickup truck which he called his "electronic brake" because it substantially slowed the vehicle when he put the key down.

It's perfectly predictable.... and some car manufacturers will tell you specifically what to do and what shielding and leakage current issues will exist. It's not always easy to predict for the end user who may not know where every ground connection in the vehicle is, but the car manufacturers have RF guys who have that information. --scott
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Scott Dorsey wrote:

MY bad. The 12 W limit is for SSB transmissions.
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The AM limit is measured as carrier power, so if you're doing a nice 100% modulation then the peak envelope power is actually eight watts because the positive signal peaks are twice the carrier level and the negative peaks are zero.
The SSB limit is actually calculated as peak envelope power directly since there's no carrier with SSB.
So comparing the two is really sort of comparing apples and oranges anyway. But most of the big illegal CB users are on AM... this may change in a couple years when the sunspot peak hits and the skip on 11M gets up to the level where it was in 1978... the CB DX craze may start up again. I hope not... --scott
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snipped-for-privacy@panix.com (Scott Dorsey) wrote:

That's not true, SSB is suppressed carrier. Carrier wave is present, but suppressed.

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It may or may not internally generated, but it's not being transmitted. if it _were_ transmitted, it would create an annoying beat note on playback unless the receiver BFO was right on the mark.
But, more importantly, it counts against your total output power... any residual carrier leakage is wasted power. That's bad, especially when the legal limit is so low you want as much as possible of your signal to actually be carrying information.
Type acceptance requirements for aircraft, marine, and commercial SSB gear have limits for how much residual carrier leakage is allowed, and it's very little. Amateur radio operators don't have any such requirements but they are expected to know what they are doing. I don't know what the CB type acceptance requirements are like. --scott
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snipped-for-privacy@panix.com (Scott Dorsey) wrote:

That also is not true. The suppressed carrier wave is being transmitted, but numerous decibels down from the maximum power being radiated. You might hear a carrier wave if the transmitter was physically close, transmitted signal very strong, but at some distance you may not hear it, signal weaker. This is just academic because all SSB transmitters today have superior carrier suppression. That was not the case years ago.

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Drifting a bit OT, but at 100% AM modulation the PEP is actually 4x the unmodulated carrier power. A 100 Watt AM tranamitter at 100% modulation hits 400 Watts PEP.
Mark
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