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Old 04-08-2012, 01:59 PM
 
1,884 posts, read 3,473,749 times
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Quote:
Originally Posted by RayinAK View Post
This is one of numerous very simple ways to explain it:

a. Every electrical component in you car, even a light bulb, has to have a negative and a positive connection to the battery for it to work. The negative pole (-) of your battery is connected to the chassis of your vehicle, and this is the ground you are referring to.

b. Lets say that you have a lightbulb in your car. For this lightbulb to energize (turn ON), it must be connected to both the positive and the ground side of your vehicle. Remember that the negative pole is connoted to the chassis of you vehicle, and that this chassis is the "ground" side.

c. So, one lead or wire is connected to the positive side of the battery, and the other lead is connected to the vehicle's chassis. However, since the metallic frame (ribs, etc.) of your vehicle is grounded to the chassis, you can have grounding points throughout the vehicle. Even the motor is grounded to the chassis via a grounding strap. The electricity that powers all of the electrical components in your vehicle travels out the positive side of the battery, through each electrical component, then through the chassis and ground points, back into the battery through the negative pole.

d. If a grounding strap, or any grounding point is loose, the electrical components affected can't work because the circuit is broken (open). In your case a "ground problem" could be a loose, or corroded, or broken ground wire or grounding point. Since the ground lead (wire) usually has a wire terminal, check this terminal to make sure it's clean and secure on the grounding area.
Thanks for taking the time to explain this so clearly.

I still need more help to understand this.

If a ground cable is completely loose and not making any contact, then the electrical path is not complete, then circuit doesn't work because there is no returning voltage, right? Wouldn't the device just works once briefly when it is first turned on because current goes from the power side through the device thereby powering it before getting to the open ground?

When a ground cable is corroded but still making contact with the chassis, some current can still flow through it right? If some current can still flow through the corroded cable, how does this affect the circuit? Would there be a large current build up in the circuit on the negative side?

Last edited by davidt1; 04-08-2012 at 02:09 PM..
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Old 04-08-2012, 02:23 PM
 
Location: Not far from Fairbanks, AK
12,809 posts, read 13,515,298 times
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Quote:
Originally Posted by davidt1 View Post
Thanks for taking the time to explain this so clearly.

I still need more help to understand this.

If a ground cable is completely loose and not making any contact, then the electrical path is not complete, then circuit doesn't work because there is no returning voltage, right? Wouldn't the device just works once briefly when it is first turned on because current goes from the power side through the device thereby powering it before getting to the open ground?
If the ground cable is completely loose, or just the ground lead of any of the electrical components are completely loose, then non of the components in that circuit work, not even temporarily. However, lets say that the ground lead is just slightly loose (not broken nor completely loose), then the electrical components in that circuit may work temporarily. All depends on how much current the electrical component draws. For example, a lightbulb probably won't draw much power and work, but the wiper or the window motor more than likely won't work very long. Also, a high current draw can result on the loose ground overheating.

Quote:
When a ground cable is corroded but still making contact with the chassis, some current can still flow through it right? If current can still flow through it, right? If some current can still flow through the corroded cable, how does this affect the circuit? Would there be a large current build up in the circuit on the negative side?
Yes, some current can flow, but again all depends on how much corrosion is present at the grounding point. That's why when connecting a wire terminal to a ground point (called bonding), you should make sure that any dirt and corrosion is brushed off the terminal and the grounding point.

Also, corrosion or dirt, or even isolating materials such as silicone or rubber, can restrict current flow, or stop it completely. Overheating at the grounding point often is caused by loose grounds.

I will give you another example: not too long ago my son's truck stopped starting. The starter was fairly new, and the battery was fully charged. Also, the problem started all of the sudden, and he told me on the telephone that jump-starting it with another vehicle didn't work. I told him to inspect each battery cable from terminal to terminal to make sure they were clean and tight against the connecting points. Upon further inspection he found that the positive cable near the battery terminal was very corroded underneath the insulation. This was the reason why the jump start din't work. The starter needed lots of current to work, but the corrosion was severe enough to restrict current flow. He replaced the cable and the problem was gone.

Last edited by RayinAK; 04-08-2012 at 02:35 PM..
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Old 04-08-2012, 06:46 PM
Status: "Spiders DO have feelings and a sense of humanity." (set 9 days ago)
 
Location: Meth capital of the world.
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A ground is a point which supplies electrons to the circuit in question(electron flow theory). If you have a bad connection (ground or positive) it can cause a lot of problems. One of the main problems is an unintended power drop at the bad connection point(due to higher than normal R at this point). In wiring this is know as a I_squared_R loss. You are dropping power at a point where it should not be dropped, this can cause heating and a lower voltage at the intended load(among other problems)(power=voltage*current....in a series loop you have a voltage divider and current distributor, voltage dropped in the wrong spot leaves less for the load, current limiting may also be a problem.).
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Old 04-08-2012, 07:59 PM
 
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A poor connection is like a low battery. Things barely work or not at all.
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Old 02-25-2013, 02:52 PM
 
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if i have a good ground from battery to block, but a weak connection from block to frame, would this effect the output of my starter?
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Old 02-25-2013, 05:34 PM
 
2,341 posts, read 1,387,153 times
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Quote:
Originally Posted by davidt1 View Post
I often hear people say check your ground when they talk about an automotive problem. Being inexperienced I have no idea what this means. Does this mean a ground cable is loose? A ground cable is shorted to something else? How does it cause a engine to stall, a component to fail, etc.?

I would appreciate very much if someone can explain what a ground problem is and how it affect engine performance. Thank you.
A "bad ground" is not apt to affect engine performance, because if that ground is bad the engine is not likely to start. However, there are all manner of other "ground wires/straps" because lots of components are isolated electrically from the engine. Everything from radio to speedo cluster to brake lights. THOSE are the grounds that are apt to get a bit corroded or loose, and cause you all kinds of fits.
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Old 02-25-2013, 05:38 PM
 
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Quote:
Originally Posted by contact_ty View Post
if i have a good ground from battery to block, but a weak connection from block to frame, would this effect the output of my starter?
No. Your starter is bolted directly to the block, and the positive battery cable goes directly to the starter.
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Old 02-25-2013, 05:53 PM
 
Location: Summerville, SC
3,383 posts, read 3,174,821 times
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Is you starter working.g slow? I believe I have seen ground wires on circuits for starters for the solenoid.

As for degraded performance I believe people have had bad grounds on sensors, that causes less then ideal readings. Which of course could degrade engine performance.

Sent from my PC36100 using Tapatalk 2

Last edited by MustangEater82; 02-25-2013 at 06:47 PM..
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Old 02-26-2013, 11:42 AM
 
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To make it simple... A circuit has to have 2 wires to be complete. The ground serves as one of those wires.
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Old 07-16-2014, 10:51 PM
 
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So how do you fix a ground problem?!
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