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Wyckedflesh
| | Posted on Friday, December 19, 2003 - 09:28 am: | 
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Most of the early brit cars (MG, Triumph, Austin, Sunbeam)I think up to 75 or 76 had a positive earth system. A few of the bikes also.
So Darthane just as a thread Hijack...watch alot of Anime?  |
Dasxb9s
| | Posted on Friday, December 19, 2003 - 10:40 am: |
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My DC theory is weak... and as I remember one of the reasons there is a "return" wire to ground in automotive applications is efficiency. If a wire to ground is attached to the chassis and the connector comes loose, breaks... corrodes... stuff stops working or works poorly... and this was a common problem in the olden days of my youth. Back when I was a youngin... almost all cars had things grounded to the chassis for "return" except for Corvettes (fiberglass bodies) and boats (non-metal hulls). Why waste all that wire.
It must have gone something like this: WHAT... you made a car out of fiberglass... how the hell we gonna ground the lighting system? You know how much production costs this is gonna add to have to provide a ground wire to the lighting system!!!
This practice of chassis ground saved wire... but did two things. ONE... cause the installation time of grounding each item to the chassis. TWO... created problems with poor grounds when ELECTRONICS were introduced into automotive application. AND electronics are sensitive to such things as a change in resistance due to corrosion or poor connection in chassis grounds. AND with RF generating devices becoming common... other problems developed. THERE MAY BE OTHER REASONS! (such as plastics becoming common in automotive application to replace metal... even though "chromed" plastic will conduct... it made no sense to wire ground some stuff and chassis ground other stuff... WIRE GROUND IT ALL... and if it is also grounded to the chassis... all the better!)
That is when the practice of wire ground to electrical system became a need... plus... it was quicker to build things when stuff just plugs into a harness... and chassis grounds did not have to be attached. SO... a wire is not being wasted... GROUND IS BEING ASSURED... as poor grounds cause resistance to increase to DC flow... thus creating a problem... PLUS... electronic components are sensitive to voltage changes... unlike the old stuff when I was a kid... so a GOOD ground system throughout a vehicle electrical system IS VERY IMPORTANT. Some electronic components in a circuit... even up-stream or down-stream from a non critical simple bulb circuit... may be affected by a problem up or down stream. Such as a poor ground.
PLUS... little loose short wires act as antennas... and things have changed since the olden days when was a kid... (pagers... cell phones... wireless computer networks)... when a loose wire or some other component sticking up to act as an antenna was not an issue. HOWEVER... now... with all the RF (radio frequency) surrounding us... a loose ground wire like in the old style way of grounding automotive lighting... can and WILL act as an antenna... and introduce RF (AC current) into the DC circuit... which has two negative aspects... basically we DO NOT want AC current in a DC system... AND... stray AC in automotive electronics is not wanted AND/OR RF in automotive electronics/computer systems is a very bad thing.
We use 100 watt transmitters in cars at my employment (check my profile for a hint) and I think it was a Ford SUV... that had the problem of... whenever the radio was keyed up... the rear windshield wiper would turn it's self on... and its not like a windshield wiper motor is a computer... BUT... it was controlled by chips. How was it fixed? It was shielded my a metal housing connected to ground... to sent any captured RF to ground... there may have also been electronic components added to send the AC current from the RF to ground... I do not have all the details.
NOW here is where my DC theory is VERY weak... I seem to remember a term called a "floating ground" which is a bad condition... causing possibly resistance at the wrong place... or the such. SO... to assure a good ground a wire is "wasted" to ground things... even though it may by reason of how it is constructed be attached to chassis ground. The key here is... when electronic and computerized systems are involved... GOOD grounding systems are a must to assure a solid circuit!
AND YOU ARE CORRECT... having the wrong bulb in after market turn signals can be problematic. These lighting system are designed to work within certain parameters. |
Darthane
| | Posted on Friday, December 19, 2003 - 09:54 pm: |
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-=sigh=- I had written like a two page response to that, and then my internet connection decided it just wasn't going to allow me to post.
Ah, well. Maybe I'll get around to it later. |
Wyckedflesh
| | Posted on Friday, December 19, 2003 - 10:10 pm: |
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hands Darthane a roundtoit |
Unibear12r
| | Posted on Saturday, December 20, 2003 - 02:20 am: |
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A floating ground is not always bad. In AC systems an Isolated Ground ( floating from local or equipment grounds)is used to ensure clean power to sensitive equipment. Some DC systems Ive had to troubleshoot were isolated totally from ground which can make it a pain in the BUTT. I have seen where one side of a turn signals socket is grounded to the metal case of the turn signal and still has two wires to hook up. In that case marching polarity matters. In my case the factory reversed wires and that became a pain in the Butt when I tested the signals and smoked more than the fuse. That was on a Kawasaki along time ago. Glad you found the problem |
Unibear12r
| | Posted on Saturday, December 20, 2003 - 02:29 am: |
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Oops that was matching polarity. |
Darthane
| | Posted on Saturday, December 20, 2003 - 04:19 am: |
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Uni, you can edit your posts by clicking the little notepad in the upper right corner, instead of posting a correction.
And I'm going to use just that function here to apologize for the however many posts there are down there, but the damned thing wouldn't let me post more than one paragraph for some reason! Isn't technology wonderful?
edited by darthane on December 20, 2003 |
Darthane
| | Posted on Saturday, December 20, 2003 - 04:58 am: |
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And since it's apparently going to let me post, and Wycked was kind enough to give me the roundtoit that I was lacking before, I'll see about retyping that response.
First of all, a '52 Dodge? Christ, Glitch, you old fart. We're talking modern marvels here, not dinosaur-era Flinstone's-mobiles. In any event, there are exceptions to every rule. However, even cars with fiberglass bodies still use chassis grounds, as the CHASSIS is still steel (or some other metal). You just have to be a little more creative in your grounding locations.
edited by darthane on December 20, 2003 |
Darthane
| | Posted on Saturday, December 20, 2003 - 05:01 am: |
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Now, chassis grounding does NOT mean that every component is individually attached to the chassis - Christ, that would be a collossal waste of time. For new Ford vehicles, for instance, there are six 'standard' grounding locations. The majority of components route to one of those six points. Corrosion is of little concern nowadays with regard to grounding points. Rust-prevention techniques have improved as well as the attachment schemes themselves. Mazda and most Japanese automakers, however, still use redundant grounding systems.
edited by darthane on December 20, 2003 |
Darthane
| | Posted on Saturday, December 20, 2003 - 05:01 am: |
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Wire grounding may sound like a wonderful idea - it would eliminate POSSIBLE problems with corrosion, as you noted. However, it would introduce loads of added cost to the electrical system in terms of increased wire gauges and obscene amounts of length. It would also necessitate an increase in inline connection sizes to pass all the grounds from one harness to the next. Such a change would probably be on the order of $20-$50 per vehicle. At 100,000 vehicles, that's only $2,000,000-$5,000,000 dollars of unneccessary cost. May not sound like much, unless you're Ford purchasing. Or DCX, or GM, or any other company on the face of the planet.
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Darthane
| | Posted on Saturday, December 20, 2003 - 05:02 am: |
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Yes, good grounds are important. Probably 25% of the problems I've diagnosed when troubleshooting can be traced back to faulty grounds. However, those are on early prototype vehicles. As stated above, grounding for new vehicles, unless assembled incorrectly or damaged (as in a crash), will easily last the life of the vehicle as is.
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Darthane
| | Posted on Saturday, December 20, 2003 - 05:02 am: |
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Voltage - another 'recent' problem, as you said. Most 'smart' components on a vehicle require a specific voltage to work properly. Enter the VREF system, which uses regulators to send a continuous 5V signal (remember Reep's speedo filter? This was necessary because someone forgot to make the important, sensitive, speedo sensor run off of a regulated signal) to the touchy electronics. They made it 5V because the vehicle can never drop that low in the first place, so there is no chance of it ever dropping below that with the vehicle running. Any variable voltage sensor runs off of a regulated signal in this manner, because even the new so called 'smart' alternators are incapable of providing a constant voltage without regulation.
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Darthane
| | Posted on Saturday, December 20, 2003 - 05:02 am: |
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Yes, loose-ended wires act as antennae. Actually, all wires do, whether they are single-ended or not. The prevalence of RF in today's world has necessitated a shift to protect certain types of electronics, as you noted. The vast majority of vehicle electronics will not be adversely affected even by taking a CB transmitter and hohlding it right next to the component. For those that include microprocessing units, case grounds are common and the most effective way of killing RFI. Some types of signal returns are also shielded, either by twisting (audio and airbag detonator circuits) or twisting/shielding with aluminum tape (crank position sensors or microphone leads).
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Darthane
| | Posted on Saturday, December 20, 2003 - 05:03 am: |
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A 'floating ground' is simply an indirect connection to ground, usually through a resistor, and is not necessarily a bad thing. In fact, some systems rely on them. In a vehicle, though, most components rely on a solid, low resistance connection to ground (negative battery) through the chassis. So it's not a good thing in cars, or motorcycles, for example. But then, that's the difference between an INTENTIONAL floating ground and an UNINTENTIONAL one. In grounding, pretty much anything unintentional is bad.
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Darthane
| | Posted on Saturday, December 20, 2003 - 05:03 am: |
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As a side note, I'm very interested in seeing an internal schematic for the flashing unit they use on the XBs. I wonder precisely how it works and if it has anything to do with this rash of people blowing things up, or if it's just the bulbs. I've never paid any attention when I've removed my turn signals (at least a dozen times between the two bikes), so I don't know if they are still 'right' or if they're 'backwards', and I don't care, because they're still the stock bulbs and it doesn't matter a rat's patootie which way they go on.
Now, let's see if it will still let me post...
Bryan |
Unibear12r
| | Posted on Saturday, December 20, 2003 - 07:35 am: |
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Thanks for the info. And you know your electricity. I dont work on DC as much as AC power systems. What you are defineing as a floating ground would be called a High Impedance Ground on AC. It could be a resistor, capacitor, inductor, or any combination there of depending on what frequencys you are trying to keep and what you are trying to shunt to ground. I have read where the car makers are looking into putting IC chips on every device on a car and then using only two wires to circle the car and power everything. The ICs on switches would superimpose a signal on the power ring to tell the ICs on devices to turn on or off. Supposed to save alot of copper weight. Even wilder-plastic conductors-doped kind of like simiconductors-and they conduct along only one direction. The curent can only flow along the wire but not side to side. It is its own insulation. Its still too brittle and high resistance yet. |
Dasxb9s
| | Posted on Saturday, December 20, 2003 - 10:50 am: |
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Darthane...
Some very good points...
Unibear12r...
Some very good information...
I LOVE THE BADWEB... there is a wealth of information out there... and I like to pass on what I have learned since the invention of dirt... BUT... I love what I learn even more! |
Darthane
| | Posted on Saturday, December 20, 2003 - 06:56 pm: |
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Unibear12 - what you are describing sounds like the networking already in use today. They go by different names with different companies (Ford/Mazda call it CAN, and there are at least two varieties of that), but everyone on the market uses some form of it.
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Darthane
| | Posted on Saturday, December 20, 2003 - 06:57 pm: |
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In certain applications, use of such a system can significantly reduce cost in the electrical system as noted, by reducing copper costs. However, there is a huge up-front cost to engineer, design, and manufacture these 'smart' modules/motors, and that is what is currently keeping such a 'two-circuit' design from hitting the market. The other thing to note here is power and ground requirements, so at the VERY LEAST, should such a system get off the ground, each motor would need 4 wires. Obviously such a component is much more expensive overall than the little two wire electric motors we all know and love. Another problem with this is that it would most likely require (at present, anyways) more than one network in the vehicle, and at least one module to do translating, due to limits on how many messages can be passed along a single network with any reliability.
edited by darthane on December 20, 2003 |
Darthane
| | Posted on Saturday, December 20, 2003 - 06:58 pm: |
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There are some very interesting things going on regarding moving in this direction with major manufacturers right now, even on the program that I'm in Hiroshima working on. Unfortunately I can't say much more than that...darned confidentiality agreements! LOL
...this whole 'can't post more than a paragraph' thing is getting really annoying...anyone with a clue want to chime in (via the e-mail in my profile) as to what might be causing this? |
Unibear12r
| | Posted on Saturday, December 20, 2003 - 08:55 pm: |
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Im finding myself behind the times on alot of things anymore. I didnt realize this move was so far along.I thought development time/cost would take longer. Even more plug in plug out car repair. |
Darthane
| | Posted on Sunday, December 21, 2003 - 08:36 pm: |
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Well, bear in mind that even the steps that I mentioned above are years off. The project I'm working on is '07 model year, I believe it is the first Ford vehihcle to incorporate this newer tech. DCX is also working something similar, but I've no idea when their system debuts on the showroom and it's a slightly tweaked system (making me think that Ford got wind of DCX's program and decided to dog their heels on it).
Course, this is all stuff that the average consumer would never, ever see or even care about. The only time a non-wiring/electrical person gives a rat's ass about wiring or electrical components is when they fail! |
Unibear12r
| | Posted on Monday, December 22, 2003 - 09:03 pm: |
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I knew there was a long lead time on some products. Three model years away and you have been involved awhile already. I hope you are enjoying Japan!
Yes at times I think the average person looks at electrical like the Medieval thought of magic. To them it looks so easy. I never say something cant be done, just that anythings possible with enough time and money. It makes them think when money's involved.
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