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Sherlock Ohms

Strange Connections Killed the Mercedes-Benz

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patb2009
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Platinum
over-engineering
patb2009   11/1/2015 1:29:53 AM
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the safety systems and the engine systems should be on independent fuses.

 

 

JABova
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Iron
Re: over-engineering
JABova   11/2/2015 10:07:02 AM
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But separate fuses cost too much :-)

William K.
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Platinum
Re: over-engineering
William K.   11/2/2015 8:45:10 PM
What should be is that designers should be forced to consider the secondary results of their actions.  More likely to happen, the companies should be forced to list every item fed by each fuse. When I say "forced", I mean not allowed to sell the products, no matter what, without the required information. That kind of force would get cooperation. AND the information to produce such a list already exists in their design files, so it should be easy.

patb2009
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Platinum
Re: over-engineering
patb2009   11/2/2015 9:22:53 PM
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thats a govt regulation and most people here hate regulations

kasone
User Rank
Iron
Re: over-engineering
kasone   11/3/2015 7:33:47 AM
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Not necessarily, if the leaders at the top instill a culture of excellence in the products, no governnment regulations are needed.

William K.
User Rank
Platinum
Re: over-engineering
William K.   11/4/2015 12:15:11 PM
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"If the leaders could instill a culture of excellence". RIGHT, the leaders primary goal is to increase share prices to make the board and the shareholders happy. Possibly such inspiration could come from lower level managers and supervisors, and sometimes it does. But the auto companies have other goals and pulls.

patb2009
User Rank
Platinum
Re: over-engineering
patb2009   11/4/2015 5:37:04 PM
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very few cultures survive a race to the bottom.

 

If your competitors can do something cheaper and sell cheaper, 

odds are you will lose the market.

 

 

rollywind
User Rank
Silver
cost vs. value
rollywind   11/23/2015 11:27:52 AM
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It has been my experience that BMW produces great mechanicals but lousy electronics and electrical products. You must know that they produced cars in the 80's and 90's specifically for the leasing market. Robust design (proper design) was not their priority.

I helped a friend remove his dash to replace several burned out light bulbs and found the PC board behind the dash to be made of similar materials to the board used in the sonobouy* dispatched at sea by the navy during ASW operations. These boards were very simple design and meant to last only about 12 to 24 hours and then sink. The board had cracked, not unusual with this material, and the solder connections were poor with several of the failures attributed to the brass light sockets detaching from the solder on board.

My daughter's BMW left tail lights totally stopped working one day. Turns out the base metal for the three light bulbs was made of cheap pot metal (white metal) and the connection to ground for all three ran through an 18 gauge wire to the car's chassis. The push on connection had charred and the wire opened due the high current and poor connection. I rebuilt this by soldering a new wire with push on connector to a spare tab on the base using a 12 gauge wire. I eventually rebuilt all of the signal light connections on the car.

We're also aware of those who think they know business when all they really know is the jargon of business--often number crunchers who, as Oscar Wilde put it, "know the price of everything but the value of nothing."   From the forward to the book: Seeing the Big Picture by Kevin Cope

I survived the '89 Quake also.

*A sonobuoy (a portmanteau of sonar and buoy) is a relatively small buoy (typically 13 cm (5 in), in diameter and 91 cm (3 ft) long) expendable sonar system that is dropped/ejected from aircraft or ships conducting anti-submarine warfare or underwater acoustic research.

J.Lombard
User Rank
Silver
Re: over-engineering
J.Lombard   11/3/2015 11:06:08 AM
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This type of list would have been very helpful to me last year when the emergency flashers in my 2005 BMW X5 became enabled, with no way to disable them. I swithed the flashers on while parking a trailer in my driveway. When I tried to shut them off, the console mounted push-button had no effect.

BMW does not use a mechanical swith to energize the flashers. Instead, the button pushes a plunger that contacts a micro-switch on a small circuit board mounted underneath. The retaining tabs on the circuit board had broken loose from the switch housing, rendering the plunger useless and the flashers merrily blinking away.

It was about 10PM and I was just wanting to call it a day. I figuerd the easiest way to kill the flashers woud be to pull the fuse for the circuit, else the battery would be discharged during the night. I suppose I could have disconnected the battery, but it is located in the rear of the vehicle, under the load deck, under the spare tire, AND under the air compressor for the load leveling shocks.

I started pulling every fuse that even looked like it had a "lighting" function label on the fuse box cover(s). After pulling about a dozen fuses, the lights were still issuing their warning message.

In a fit of desperation, I pried the switch housing out of the console and discovered the mechanical failure. I was able to poke the micro-switch with a small screwdriver and deenergize the flashers, allowing a permanant fix later.

I can just imagine what a poor outcome this could have caused if this had happened at the airport paking garage or similar not-home location. If a listing would have been provided in the manual, the fuse could have been located and the emergency (flashers) alleviated.

John_Reed
User Rank
Gold
Re: over-engineering
John_Reed   11/3/2015 11:14:47 AM
Spending over $20K for a product and not being able to get documentation that the owner could use to troubleshoot, or at least supply to an independent technician for repair is an outrage.

The last official car manuals I bought was for a '93 Taurus. I think the service manual cost $100 and the wiring diagrams another $15 or $20.

If the "consumer advocates" in Congress want to accomplish something they ought to require that auto manufacturers supply all service manuals on a DVD or other medium at a reasonable cost as an option for the buyer.

 

vandamme
User Rank
Gold
Re: under-documenting
vandamme   11/3/2015 11:20:34 AM
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If somebody builds an open source car, I'll buy it.

Larry M
User Rank
Platinum
Re: over-engineering
Larry M   11/4/2015 12:46:35 PM
And include lifetime map updates for the GPS.  $200/year for updates doesn't compare well to $39.00 for a standalone GPS with lifetime maps.

patb2009
User Rank
Platinum
Re: over-engineering
patb2009   11/4/2015 5:36:00 PM
The manuals should be supplied on either a USB or a DVD as a standard.

bob from maine
User Rank
Platinum
Complex cars
bob from maine   11/2/2015 10:25:19 AM
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MB makes some extraordinarily complex cars and in my experience, they are more than helpful in troubleshooting electrical issues, providing copies of schematics, Recall notices, TSBs to any who ask. Tying a passenger occupancy sensor to the engine idle solenoid - along with probably a bunch of other stuff, makes troubleshooting really tough. I've spent more than my share of time proving that the observed problem can't possibly exist based upon some aftermarket shop manual. I'd say finding an intermittent problem in the seat sensor was a real stroke of luck. That would have been a good day to buy a lottery ticket I think.

 

Larry M
User Rank
Platinum
Two similar instances
Larry M   11/2/2015 4:03:20 PM
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It reminds me of two similar instances. The MB wasn't the only car Made by Monkeys.

 

1) The taillight fuse on our 1976 Datsun B-210 would blow every couple of years. It wasn't frequent enough to chase down. But one day I was cleaning the car and lifted the carpet for the front passenger seat. Underneath was a four-wire flat cable. As I lifted it from the floor pan to vacuum under it, it stuck, then came away. There was a tiny, sharp metal burr which had penetrated the insulation. It wasn't long enough to contact the wire strands--except when a passenger planted a heel right on top of the cable coincident with the driver pressing the brake. I filed the burr off and never blew another fuse. Just serendipitous that I found it--and recognized what I found. I probably never would have found it if actively looking for it.

2) There doesn't seem to be any strategy as to what options are on what fuse circuits. I was trying to diagnose some problem on my GF's 2006 GMC Yukon XL and I couldn't get any response at all on the OBD II port. I had fearful visions of dollar signs as I imagined a failed Engine Control Module. Fortunately these things are now widely discussed on internet forums. After a quick search I asked her "Has one of the cigarette lighter sockets on the console stopped working?" She replied, "Yes, I loaned the car to my son-in-law a few years ago and it hasn't worked since." There doesn't seem to be a good reason why these two functions are fused together (except, of course, that neither is an immediately essential function). BUT it sure would have been nice had GM documented that. The owner's book just describes that fuse as cigarette lighter, doesn't mention the OBD II function.

sdgengineer
User Rank
Silver
Re: Two similar instances
sdgengineer   11/4/2015 12:36:07 PM
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My 2000 GMC  truck did the same thing.  I got a new ODBII/CAN reader, plugged it into the port to see how it worked and ...nothing.A quick google search revealed that the lighter fuse powered the ODB reader as well.  Probably standard across GM cars..

patb2009
User Rank
Platinum
poor understanding of value
patb2009   11/2/2015 7:38:34 PM
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I don't mind having 3-4 fuse boxes in a car... In fact it eases troubleshooting,

but I really hate tying things together.

 

it's very poor value engineering.

 

 

Larry M
User Rank
Platinum
Re: poor understanding of value
Larry M   11/3/2015 9:13:44 AM
NO RATINGS
Patb2009 wrote "I don't mind having 3-4 fuse boxes in a car... In fact it eases troubleshooting."

Umm, yeah, the Yukon XL does have multiple fuse "boxes." That didn't stop GM from putting the OBD II port and cigarette lighter on the same fuse.

John_Reed
User Rank
Gold
shorts and opens
John_Reed   11/3/2015 10:46:48 AM
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Given accurate diagrams, or even better, computerized wire listings, opens are easy to find as long as you can get physical access to conductors. Shorts are another matter, and intermittant shorts can consume inordinate amounts of time and expense.

At my plant we had two contractors simultaneously installing two major upgrades in the same bay of a building. Both teams had hand drawn wire lists and both started numbering their wires sequentially with wire #1. Many of the wiring junctions were in boxes that were very hard to access. There were no terminal strips in many of the junction boxes and we ended up with many cases where the two systems had totally unrelated conductors tied together labeled with identical wire numbers.

 It was a perfect storm of confusion. When checkout began, some components immediately went up in smoke. Wire #1 of system A was connected to wire #1 of system B. When this was corrected we got all the way to wire #3 before dealing with the next error.  It took months to correct all the errors. All this waste of time and effort would have been avoided had management simply specified to the contractors a numbering system to use in identifying cables and conductors.

There is no excuse for failing to document every conductor in a newly constructed facility in a data base, which can be sorted to show all the terminal points connected to any electrical circuit node or all the electrical nodes on each terminal strip or subassembly connector.

 

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