451 shielding problem (Re: RFI and cruise control)

nscaler · 05-06-2009, 07:46 PM

I had my car in for it's service today and found out about the problem I have been having with throttle control loss due to RF interference with the 451 module. The 451 forum is all abuzz with this. Certain components in the module are susceptible to Radio Frequencies. The friend I was talking to at the dealer said that every time he drove past a certain local hill with lots of transmitters (TV, radio and repeaters), his throttle would stop working. I had the same problem with my ham radio. If I transmitted on certain frequencies with too much power (watts), my throttle stopped working too.
So I'm checking on getting some shielding for my 451 Cruise Control.

First I have to get my car back from being serviced. The 2.0 upgrade would not work (other thread).

SuperGeek · 05-06-2009, 08:51 PM

You're talking about the Area 451 cruise, right? By "throttle stopped working" do you mean the automated control, but shutting it off worked, or you had no control over throttle at all?

Old smart · 05-07-2009, 04:01 AM

Radio frequency interference is a situation known by smart from the beginning. There is a warning in the OpMan about using communications gear without an external antenna while driving (see: >>Technical data. Engine electronics). The same problems could be caused by strong outside RFI.

So far no problems here with me, even though the Hampton Roads area is flooded with military RF of all types and frequencies. The worst is probably Navy radar; they can cause a radio to hum as the beams sweep by.

Big Panda · 05-07-2009, 04:17 AM

Funny you should mention this "OS"....years ago, while living in FL, a friend of mine bought a new Lincoln Town Car. The first week he had it he drove several times to and from Tampa to Orlando across I-4. Each and every time he got in one stretch of I-4, the car would just QUIT! He would coast off to the side of the road and stop. When he tried to restart, it would fire right back up and away he would go.

This went on for a couple weeks before he could get it back into the dealership. Well, long story short, it was a local airports radar passing through that area each time that was killing his TC. There was also a report of a Wendys in that area that every time the radar passed through, the electronic cash register would 'go down'. I heard they had to place a LEAD SHIELD around the machine to keep it from shutting down.

So the story on our smarts IS very believable.......I've been lucky and not had ANY issues; KNOCK ON WOOD!

jsenka · 05-07-2009, 06:37 AM

I went to the 451 site and found one thread related to one particular user who encountered some RFI issues. The problem showed up as a Traction Control anomaly. The individual was using a 25W 2-way radio, and some aluminum foil shielding around the CC module made an improvement.

Keep in mind that his RF source was onboard, not from an outside source.

It certainly doesn't seem to be a widespread issue and there haven't been any posts to that thread since mid-March.

chieftmc · 05-07-2009, 06:47 AM

Quote:

Originally Posted by nscaler

...The 451 forum is all abuzz with this.....

Which one? I cant' find it either

jsenka · 05-07-2009, 07:00 AM

I did find it, and edited my original post.

Its under the Warranty Support section about a problem with Traction Control.

Old smart · 05-07-2009, 07:04 AM

A very cursory look-see on the internet comes up with any number of RF shielding materials, from rigid panels to foils to meshes to soft fabrics. There are specific material characteristics to shield against specific frequency ranges. The OpMan notes smart’s sensitivity to RF from <50MHz (6M) to the 0.25 Meter band (about 1200 MHZ) with different powers out (or in?). This is almost all of VHF and the lower half of UHF. The 900MHz mode of my cellphone is within this range thus I ought not use it while the car is moving. So the trick is to determine exactly what electronic components become confused, and what RF shielding material(s) can best protect them.

I shudder at the thought of having an 18-wheeler alongside at 65MPH while he is CB-ing someone at full gain and frying my wire!

chieftmc · 05-07-2009, 07:11 AM

Quote:

Originally Posted by jsenka

I did find it, and edited my original post.

Its under the Warranty Support section about a problem with Traction Control.

Oh, thanks. I remember that discussion !

nscaler · 05-07-2009, 04:28 PM

I am working on the shielding issue. And this only affects the 451 Cruise Control. Your cellphone is safe - very, very low power output. After I get some shielding, I'll try my 2m radio (outside ant.) at 50W and see if it shuts down the throttle like it did before.
This is actually a non issue for most smart cars. Just letting anyone know where there are (rare and minor) problems with aftermarket devices.
Simply turning the engine off and back on fixes it.