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ufcrusher
02-04-2001, 01:02 AM
Just out of curiousity, what would happen to a car if the engine and the electronics werent grounded? Plus no wire harnesses were actually attached?

Give me stereo or computers and i would know what would happen, but for a car, I have no clue?

KoalaFD
02-04-2001, 10:30 AM
Here I sit, confused by your question....

What?

lsinteg
02-04-2001, 11:32 PM
Nothing would happen because you have no power to operate anything. Take the ground off your battery and see what happens.

ufcrusher
02-05-2001, 01:22 AM
So, you are saying that if the engine wasnt grounded (not the battery, that was grounded) the car shouldnt work? The grounding would most probably have to do with electronics, such as the engine computers and other electronic parts. In terms of actual operation of the engine, it was working, but not properly. I.E. - making weird noises, check engine light coming on, etc.

Well i guess I will find out tomorrow from my mechanic.

Ice-9
02-05-2001, 09:53 AM
Quick crash course in electrical engineering:

You can only get current flowing through a difference in voltages. You need a ground so that you have a potential drop. Your car has a +12 (active) and a 0 (ground). That way, you can get 12 volts (approx.) to all your systems.

If, say, your battery is grounded but your radio isn't, your radio will not have power, even though your other systems will. Simple as that - there's no potential difference across the terminals, so there's no current. Also, if your ground is somehow connected to +12 V, you'll get other weird problems, because there still won't be a voltage difference across the terminals. If you didn't get most of that (which I probably won't if I read back through it), you should let your mechanic deal with it.

p.s. I'm an ex-EE major who can't even find the short in his own damn car's electrical system, so my advice is HIGHLY suspect.

ufcrusher
02-05-2001, 02:47 PM
Well apparently from what the mechanic says, their are multiple wire connections that are not properly hooked up, and several areas that are not grounded. Any one of these faulty installations could apparently trip out my cars entire electrical system. (RPM's are at 2000 -3000 when idling! and jump another 500 - 1000 if I turn on anything in the car) Every electronic component that I can physically manipulate (without getting into the engine and toying around with all of that fun) is operational. However, my mechanic is telling me that the RPM's are being caused by the computer being improperly wired and grounded.

As for source flow and impedence, etc. I am aware of all that. I was more or less trying to figure out why I could see no outward signs of all of these difficulies with the exception of the high RPM's and weird noises. I wasnt sure if standard electrical knowledge would easily translate into an isolated system such as the motor. I assumed it would, but I was wondering if anyone knew anythign in particular.

KoalaFD
02-05-2001, 06:31 PM
Uh....

I'm still confused.
Here's some non-impedance, caveman thinking for you:

If it idles too high, turn the idle screw and lower it.
If it's not that, check your ECU.
If it's not that, hit it with a big, big wrench.

hapoo
02-05-2001, 06:35 PM
Originally posted by KoalaFD

If it's not that, hit it with a big, big wrench.

Thats the universal technique. It works for everything!!

sbp
02-06-2001, 01:47 PM
Originally posted by hapoo

Originally posted by KoalaFD

If it's not that, hit it with a big, big wrench.

Thats the universal technique. It works for everything!! Especially for hapoo's head!! :D

katmai
02-06-2001, 10:01 PM
I've had to re-wire lots of sports cars, mostly British, and I can tell you most mechanics FEAR wiring problems!

Usually they do relate to faulty grounds and connections being bad or weak. Do a search sometime for "Lucas Curse" and you'll find a mind boggling array of what wiring/electrics can do. I had a friend who's Lotus Europa burned up in his garage, after sitting all winter, for no apparent reason. Jaguars are known for things like the wipers coming on when the radio is turned off and the horn honking on making a left turn!

I dunno what else to say but GET A PROFESSIONAL!!!

Crazyace
02-20-2001, 06:30 PM
Ahh, hate to admit it... hhee.. But serious.. The electrical thing.. Thier is an easier way to understand the concept..

You need 3 things to have electricity. Source, path, and load. If either one of the 3 are not present, you do not create electron flow. Electricity is the flow of electrons.. Negative electrons are stimulated by the positive charge of a source. The electrons goto the positive source due to the natural attraction (boys like girls, electrons like protons).. If thier is not path, the electrons cannot reach the protons, therefore, no electron flow is created because thier was no reason for them to travel in the first place. The only reason they travel is to reach the protons. Electricity is the energy created by electron flow.

Nanotech9
02-21-2001, 11:31 AM
Originally posted by Crazyace
...goto the positive source due to the natural attraction (boys like girls, electrons like protons...

maybe thats my problem... girls aren't attracted to boys. I'm gonna have to break the laws of nature to get a girlfriend!

theHNIC
02-21-2001, 11:37 AM
Originally posted by katmai
and the horn honking on making a left turn!

My Cadillac done that...so i unhooked the horn...all is well now...

Since i cant use my horn i use my finger and throw rocks at people...

[Edited by gotmilk on 02-21-2001 at 11:44 AM]

theHNIC
02-21-2001, 11:41 AM
OOPS

[Edited by gotmilk on 02-21-2001 at 11:44 AM]

Ice-9
02-21-2001, 05:11 PM
Wow, what a good idea. Whoever owned my car before me disconnected the horn when he put in the Momo wheel, so I should really start keeping rocks in the door bin to throw at people. I'd probably run out pretty fast, though, considering how people drive in Berkeley.