Cars: It's nice to know electronics!

I'm sure glad I am a "mechanical type" and know electricity/electronics!
Lately I've had a lot of repair work to do with my car and a new/used truck
I purchased.
More and more vehicles are more electronic than electrical, but no problem if you know how these things work.
(Then many consumer products I purchase lately do not work out of the box. They need to be repaired or modified to work properly. I guess quality control is a thing of the past now? Anyway no problem for me! I just redesign the thing so it works.)
As to the vehicles, I've been poking around a few automotive forums lately and it is quite interesting to say the least! Go visit some of these and look at the electrical questions/answers!
The very newest vehicles now have data communications between various components including the radio. Or have electronic audible warning sounds connected to the car speakers via some sort of interface. And some of this stuff is quite important that it work, so self testing is built in. No factory radio on the data bus and the car will not start!
In the past people have replaced their factory stereos with an after market stereo with no problem. Now they do this and mess up the works!
Or they go and change the tire sizes on trucks without taking into account that the speed of each tire feeds into a computer. Then they have trouble!
Or they add electronic gizmos to a wire - any wire which works, then have problems with fuses blowing. No attempt to determine the amperage capacity of the circuit, how much amperage is being drawn by existing components, and how much amperage the new gizmo will draw.
To top it all off, automotive stores are still in the 60's with the multimeters they sell. They only have a 10 amp capacity. Yet vehicles commonly have 15, 20, and 30 amp circuits these days! So how is any consumer supposed to be able to measure these circuits using the test equipment available to them via their auto parts store?
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wrote:

Total bullshit.
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wrote:

It was no different when it fed into a gear, and pushed an analog speedometer display. All it changes is the calibrated accuracy of the readout device. Since the DOT only requires a + or - 3 MPH accuracy, it wont cause too much error depending on the size of the change, which today could be huge.
Modern speedometers do not monitor wheel rotation. Many actually use ultra-sonic sonar pointed at the road.
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Well maybe it's better if ordinary consumers don't go messing with high current circuits.
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FunkyPunk FieldEffectTrollsistor wrote:

Actually, that does happen if an aftermarket replacement radio has wiring on an ISO connector that mistakenly shorts out a contact previously reserved by the car manufacturer and used on the OEM factory radio for CAN Bus.
--
Adrian C

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At least in Finland you can find DC capable clamp type multimeters on several auto parts stores. Those can typically measure DC currents up to 200-300A at 100 mA resolution. So there are measuring instruments that suit for those measurements available. By the way those clamp multimeters are very nice to have tools when workign with car electronics: You can measure the current from practically any wire you can access and you don't need to disconnect anything to get the reading (does not disturb the car electronics in any way). Here are some links to some reasonably priced clamp multimeters that can measure DC:
Uni-t UT203 Digital Clamp Multimeter (AC/DC 600V 400A Max) http://www.dealextreme.com/details.dx/sku.15220~r.85273703
PIHTIAMPEERIMITTARI AC/DC http://www.biltema.fi/osteri/osteri.cgi?sivu=skriptisivut/index_kauppa.htm&linkki 281.htm&tuote281
-- Tomi Engdahl (http://www.iki.fi/then /) Take a look at my electronics web links and documents at http://www.epanorama.net /
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This raises an interesting discussion.
It used to be that every Sunday morning would see the men of the neighbourhood tinkering under their car bonnets.
The advent of the Engine Management Unit has removed the need for all that, because if the battery is good and there's fuel, the car will start first time, every time, even in the coldest and wettest weather.
Thus, in the words of, "1066 And All That", the EMU is A Good Thing.
Another "Good Thing" might be the ABS, the Anti-Lock Braking System, but the jury is out on that because the number of times that you might need it is small.
The rest of the electronics? Candy Floss fluff.
To be reading this at all suggests that you are in possession of a computer whose capability exceeds that by several orders of magnitude of the computers of only 10 years old.
What might we do with these computers?
Well, it seems that we have the processing and displaying power to diagnose any electronic faults that might come up on the over-provided electronics in cars. The only connection lacking is to the CAN bus. We have oodles of others interfaces, Centronics, Keyboard, USB, Firewire, DVI, so the provision of one more interface isn't going to be daunting.
Now there _ARE_ boxes on the market that will do the job for you, but how about if we gang together and provide an open-source solution?
This will resolve the problem of not knowing the impact of obscure electronic alarms, a situation that would not have arisen in the days of the Sunday-morning tinkering days.
Danger of tampering with car electronics? Even one of the leading players in the field, Omitec of Devizes UK does not have data agreements with all car manufacturers, and gets its information by poking about under the bonnet with the collusion of a second-hand car dealer in Bristol, UK!
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On Mon, 9 Mar 2009 08:41:14 -0000, "Alun"

Bullshit. What makes a car start up right away in modern engines is the absence of a carburetor. Fuel injected engines start up ALL the time.
That is true when the nearest computer is miles away as well.
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What "boxes" are there?
serious question
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snipped-for-privacy@privacy.net wrote:

Start here
http://en.wikipedia.org/wiki/On-Board_Diagnostics
& from that ...
http://www.geekmyride.org/wiki/index.php/Open_Source_OBD_software
--
Adrian C

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I have actually been thinking abt buying a ScanGuage
http://www.scangauge.com /
I have 2000 Mazda Protege and was thinking it may actually pay back in that it could give me real time gas mileage info
Advice?
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Ok but do you actually think it could PAYBACK itself if used to monitor real time gas mileage and thereby tweak driving style to get best efficiency?
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