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Ford does it *again* (more fires)
http://www.cnn.com/2005/US/06/16/for...les/index.html I'd say it's unbelievable, but it's not. Ford's got a long and, uh, glowing track record of this kind of stupid ****. What's novel about this one is the cause: this time it's not poorly-designed alternators or poorly-designed ignition switches or poorly-designed transmission parking pawls or poorly-designed fan clutches or poorly-designed gas tanks causing Fords to be deathboxes. This time, it's the cruise control deactivation switch that causes parked, unattended, switched-off Fords to self-immolate. Yishk. DS |
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#2
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Daniel J. Stern wrote: > http://www.cnn.com/2005/US/06/16/for...les/index.html > > I'd say it's unbelievable, but it's not. Ford's got a long and, uh, > glowing track record of this kind of stupid ****. What's novel about this > one is the cause: this time it's not poorly-designed alternators or > poorly-designed ignition switches or poorly-designed transmission parking > pawls or poorly-designed fan clutches or poorly-designed gas tanks causing > Fords to be deathboxes. This time, it's the cruise control deactivation > switch that causes parked, unattended, switched-off Fords to > self-immolate. > > Yishk. > > DS I guess I haven't run across this specific Ford brake switch but it sounds like it measures *brake fluid pressure* -- assuming that the report is accurate. If this is true, why don't they use a momentary NO switch on the brake pedal (mechanically) like everyone else? And I'm not trying to sound smarter than Ford engineers, but seriously, to activate the brake lights, signal the ECM of braking, and/or cut cruise operation -- I would much rather monitor brake pedal motion. It would be fine and dandy to have a pressure transducer AS WELL, for double checking purposes. If a transducer were to fail it would pose a low current, 5 volt threat to the brake fluid only with the key on verses a 12 volt 10-20 amp fused circuit hot at all times. What gives? Toyota MDT in MO |
#3
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Comboverfish wrote: > I guess I haven't run across this specific Ford brake switch but it > sounds like it measures *brake fluid pressure* -- assuming that the > report is accurate. If this is true, why don't they use a momentary NO > switch on the brake pedal (mechanically) like everyone else? And I'm > not trying to sound smarter than Ford engineers, but seriously, to > activate the brake lights, signal the ECM of braking, and/or cut cruise > operation -- I would much rather monitor brake pedal motion. It would > be fine and dandy to have a pressure transducer AS WELL, for double > checking purposes. If a transducer were to fail it would pose a low > current, 5 volt threat to the brake fluid only with the key on verses a > 12 volt 10-20 amp fused circuit hot at all times. What gives? > > Toyota MDT in MO Actually they do monitor the brake pedal postion to turn off the cruise control. The switch in the brake line is a redundnat safety feature. It opens if the pressure in the line is above 125 psi. The switch is used on most Fords, but only certain model trucks seem to be fire prone. For some reason, in some vehicles, the power feed to the switch is live all the time. In other vehicles it is switched. In all cases it is fused (7.5 amp fuse in some/most/all cases?). I have no idea why they use a live feed in some vehicles. I also don't really understand the failure mechanism. It is alledged that only a certain batch of switches is bad. Who knows. I have already seen one report where someone was caught torching his house and trying to blame it on his truck. Until the story broke, there were only a few cases in the NHTSA database. After the first stories, the number of complaints sky rocketed. Supposedly a sure sign of a problem is a cruise control that stops working. Is brake fluid especially flammable? I thought it was not easy to ignite. Shouldn't a 7.5 amp fuse be sufficient to prevent a fire in the wiring? Seems like a weird one to me. I'd hate to have to explain the live feed to the switch. Regards, Ed White |
#4
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On Fri, 17 Jun 2005, Comboverfish wrote:
> I guess I haven't run across this specific Ford brake switch but it > sounds like it measures *brake fluid pressure* Yep. The rest of the domestic auto industry figured out it was unnecessarily problematic to detect brake application with a hydraulic pressure switch...in 1961 or so. > If this is true, why don't they use a momentary NO switch on the brake > pedal (mechanically) like everyone else? They do, they just *also* use this dumbassed always-live hydraulic switch. > I'm not trying to sound smarter than Ford engineers Er...why not? You've given every indication in every one of your posts I've seen that you're considerably smarter than many of Ford's alleged engineers. > a low current, 5 volt threat to the brake fluid only with the key on > verses a 12 volt 10-20 amp fused circuit hot at all times. What gives? if the failure mechanism is as described (switch diaphragm ruptures, brake fluid seeps into electrical chamber of switch, conducts electricity poorly but enough to cause a high-resistance path to ground, which heats brake fluid up to the burn point, fire ensues) then it's entirely possible that the current rating of the 7.5A fuse is not exceeded at any time in the process. Remember, you can start a fire with nothing more than a Brillo pad and a "dead" 9v smoke alarm battery. DS |
#5
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On Fri, 17 Jun 2005, C. E. White wrote:
> Actually they do monitor the brake pedal postion to turn off the cruise > control. The switch in the brake line is a redundnat safety feature. Yeah, it senses you've left the vehicle unattended and switched off, and proceeds to burn it to the ground. For extra safety 'n' stuff. > For some reason, in some vehicles, the power feed to the switch is live > all the time. I have no idea why they use a live feed in some vehicles. Because for those specific vehicles, it allowed them to save $0.01 per vehicle in wire not used. That is how Ford (among other companies) make decisions. Pennies make promotions. > Supposedly a sure sign of a problem is a cruise control that stops > working. I know a lot of people who never use their cars' cruise controls. > Is brake fluid especially flammable? Yep. Flashpoint is typically around 125=B0C. > I'd hate to have to explain the live feed to the switch. Same here. Though by now, a simple "Well, y'see, I work for Ford..." would be completely sufficient explanation. DS (but not an excuse) |
#6
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Daniel J. Stern wrote: > They do, they just *also* use this dumbassed always-live hydraulic switch. OK, 'cause I've never seen a Ford without a brake pedal mounted switch. There has to be a reason (regardless of merit) that the bean-counting cheapskates at Ford would authorize a redundant switch. It may have been to *ironically* appeal to the safety crowd, or perhaps there is some goverment incentive for added safety features. > Remember, you can start a fire with nothing more than a Brillo pad and a > "dead" 9v smoke alarm battery. Perhaps Ford could build their redesigned hydraulic switches to include a tiny capsule of chlorine, so that during most assured failure, the chlorine would react with the brake fluid and cause a much hotter, more pleasing fire. Our products are hot, hot, hot! Toyota MDT in MO |
#7
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C. E. White wrote: > Actually they do monitor the brake pedal postion to turn off > the cruise control. The switch in the brake line is a > redundnat safety feature. It opens if the pressure in the > line is above 125 psi. The switch is used on most Fords, but > only certain model trucks seem to be fire prone. For some > reason, in some vehicles, the power feed to the switch is > live all the time. In other vehicles it is switched. In all > cases it is fused (7.5 amp fuse in some/most/all cases?). I > have no idea why they use a live feed in some vehicles. I > also don't really understand the failure mechanism. It is > alledged that only a certain batch of switches is bad. Who > knows. I have already seen one report where someone was > caught torching his house and trying to blame it on his > truck. Until the story broke, there were only a few cases in > the NHTSA database. After the first stories, the number of > complaints sky rocketed. Supposedly a sure sign of a problem > is a cruise control that stops working. > Is brake fluid especially flammable? I thought it was not > easy to ignite. Shouldn't a 7.5 amp fuse be sufficient to > prevent a fire in the wiring? Seems like a weird one to me. > I'd hate to have to explain the live feed to the switch. > > Regards, > > Ed White Thanks for the reply, Ed. Yes, brake fluid vapor will catch fire rather easily. It is hard to believe that it would do so in a closed system devoid of air, but then -- think of spontaneous combustion WRT petroleum products. Toyota MDT in MO |
#8
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Comboverfish wrote:
> > Daniel J. Stern wrote: > > > They do, they just *also* use this dumbassed always-live hydraulic switch. > > OK, 'cause I've never seen a Ford without a brake pedal mounted switch. > There has to be a reason (regardless of merit) that the bean-counting > cheapskates at Ford would authorize a redundant switch. It may have > been to *ironically* appeal to the safety crowd, or perhaps there is > some goverment incentive for added safety features. Probably because the (Ford quality) pedal activated switch had too high a failure rate. Picture the typical driver applying the brakes to slow down and then having the vehicle accelerate when they let up on the pedal. Wasn't it Ford (Crown Victoria) that had the single contact brake pedal switch operating both the brake lights and the transmission shift interlock? This resulted in some police cars with their brake lights wired to flash being accidentally knocked into gear when the flasher signal fooled the interlock into thinking that the brake was depressed. -- Paul Hovnanian ------------------------------------------------------------------ Karate is a form of martial arts in which people who have had years and years of training can, using only their hands and feet, make some of the worst movies in the history of the world. -- Dave Barry |
#9
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Daniel J. Stern wrote:
> C. E. White wrote: > >> For some reason, in some vehicles, the power feed to the switch >> is live all the time. I have no idea why they use a live feed >> in some vehicles. > > Because for those specific vehicles, it allowed them to save > $0.01 per vehicle in wire not used. That is how Ford (among other > companies) make decisions. Pennies make promotions. If the problem is degradation of the barrier between the wire and the brake fluid, then having it live all the time would make no difference as to whether or not the vehicle is going to catch on fire at some point. Having it only live when the key is on means that the car would catch on fire while people are in it, rather than while it's empty. (More danger to human life?) |
#10
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On Fri, 17 Jun 2005, Old Wolf wrote:
> Having it only live when the key is on means that the car would catch on > fire while people are in it, rather than while it's empty. (More danger > to human life?) That's one way of looking at it. Another: More people dumb enough to buy Fords ejected from the gene pool. |
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