Question About Automotive Ground

shortbus

Joined Sep 30, 2009
8,593
Much less complicated meaning they are less sensor dependent.
Can see you haven't worked on a Colorado or Canyon, with the Atlas engines in them. :) I replaced the timing chain and sprockest last year and just last week it set a new code for the anti- vibration ones. Not going to pull the engine for that, Truck only has 10K miles on it. Only bought it because all of the good second gen s10's aren't for sale. I sure miss those 4.3 V6's.
 

Thread Starter

Back to school

Joined May 22, 2019
106
@Back to school There have been times I could have sworn I understood something a certain way only to discover I either learned it wrong or remembered it wrong. I believe there's no shame in being wrong or admitting it. In fact, I'd rather say "I was wrong" or "I don't know" than to try to give a factual answer that is in error. Answering when one doesn't know the answer is the fastest way to look foolish (for me). Not saying you were foolish, only that I (we) disagreed with your assessment of the term "Bad ground". Believe me - I've made a LOT of mistakes here on this forum. But I've learned from them.

Glad you've come to a better understanding of the topics we've discussed. Now - Stay Healthy.
[/QUOTE]

I think I said this in an earlier post but my attitude has always been, I don't care about being right, I care about getting it right. This probably explains why I've always asked a lot of questions. I once heard someone say, "The only stupid question is the one you didn't ask." I took that to heart! :D
 

Thread Starter

Back to school

Joined May 22, 2019
106
Can see you haven't worked on a Colorado or Canyon, with the Atlas engines in them. :) I replaced the timing chain and sprockest last year and just last week it set a new code for the anti- vibration ones. Not going to pull the engine for that, Truck only has 10K miles on it. Only bought it because all of the good second gen s10's aren't for sale. I sure miss those 4.3 V6's.
No, I have never worked on either vehicle or the engine. GM has gone to OHC on many if not all of their smaller engines. Is the Atlas an OHC engine?
 

Thread Starter

Back to school

Joined May 22, 2019
106
That's the ones I had. It was the lighting sockets that gave me fits.
For a couple of years in the 60's all VW bugs came through our port here outside of Detroit. They all had primer on them but no paint. At the time there were import incentives based on the percentage of work content done in the US. I apologize if we were to blame. :)
Nothing was worse than the Lucas systems the Brits used. A friend of mine had a Triumph in high school and he was constantly working on the electrical system in the car. I'd estimate the car sat 2 days for every day it ran. That might even be generous?
 

bwilliams60

Joined Nov 18, 2012
1,398
I stopped reading. My eyes are bleeding. 104 posts in an we are still trying to figure out what a "bad" ground is in a car.
Good ground = 0 volts. Negative battery post.
Above 0.3 volts = excessive resistance. Voltage drop test.
Full source voltage = open circuit.
Ohms Law dictates this to be true. Draw out a circuit anf do the math. It is all right there.
And even if it is a wire that is down to its last few strands, it will produce a voltage drop across the connection. That is why we use the power source as our reference and not the body/chassis or engine. That is why Power Probe puts long leads on their tools. So you source the battery. Last thing. You need 10-20 amps going through the circuit to do a proper voltage drop test.
And yes, 40 years plus, auto, truck and Professor. Live, eat, breath Auto Electric. Sorry for being so short. Our trade needs to rethink the way we teach oir young techs. It is not written in books and most people dont teach them correctly. Old school ways dont work anymore.
CAN BUS did nothing to the circuit except split it in half and add communication wires. Its not rocket science.
 

Thread Starter

Back to school

Joined May 22, 2019
106
@bwilliams60
LOL. I did say 20 posts ago I think this topic has run its course. Since then the topic has morphed in to other topics. Also, although I found it interesting most of what was written as responses had to do with how to fix the problem which wasn't my question. If the truck was mine I would have had no problem fixing it. The question was about the nature of automotive ground with an brief explanation of why I was asking. My apologies. I'm sure you've shut it down now.

BTW, it actually is rocket science now. CAN is even used in the space program. LOL
 

MisterBill2

Joined Jan 23, 2018
8,803
For a couple of years in the 60's all VW bugs came through our port here outside of Detroit. They all had primer on them but no paint. At the time there were import incentives based on the percentage of work content done in the US. I apologize if we were to blame. :)
Nothing was worse than the Lucas systems the Brits used. A friend of mine had a Triumph in high school and he was constantly working on the electrical system in the car. I'd estimate the car sat 2 days for every day it ran. That might even be generous?
I have heard that the reason the Brits drink warm beer is because they have Lucas refrigerators. I have not been able to verify that, though.
 

MisterBill2

Joined Jan 23, 2018
8,803
@bwilliams60
LOL. I did say 20 posts ago I think this topic has run its course. Since then the topic has morphed in to other topics. Also, although I found it interesting most of what was written as responses had to do with how to fix the problem which wasn't my question. If the truck was mine I would have had no problem fixing it. The question was about the nature of automotive ground with an brief explanation of why I was asking. My apologies. I'm sure you've shut it down now.

BTW, it actually is rocket science now. CAN is even used in the space program. LOL
Once again, then, I offer my explanation of "ground", which does apply to cars and motor vehicles in general.
"Ground" is a theoretical concept that describes a zero resistance, zero impedance plane that is usually connected to the power source negative terminal. In reality it is not quite that way.
 
I do not understand why some have a hard time grasping the concept of a dedicated vehicle sensor ground. It needs to be on the same level of ground as the controlling model is so the input signal is correct. It is a simple fact that reference low on this circuit has multiple wires, terminals and a return path to ground at the battery & alternator. This where ground start when running, it’s just easier in some cases to measure at the battery. I agree that a voltage drop of 0.4 - 0.3 is too high but it is writing in service info for 2020 vehicles much less 1980. While I never said this was normal but is “MAX” only. Having 0.010 - 0.050 voltage drop is preferred. I would be checking the usual suspects on the vehicle as G100 & G101 mounts the computer grounds on the intake, back of a cylinder head and and even a stud-headed bolt on a thermostat housing. Engineers make mistake as well as I am not their “Professor”, only a season technical service person that my experience can diagnose the problem. Not having vehicle repair experience is no reason to get anyone’s nickers twisted. The training today to a certain degree has been dumb-down as compared to 40 years ago, forcing the service tech to rely on parameters seen on a scan-tool. This reduces time and increases the accuracy of the repair. Although powered test lights are useful, if the diagnostic flow chart does not call for their use, the tech may find the root cause but takes longer, because they strayed from the engineers testing.
On a test board or vehicle, ohms law does not exactly add up even with a $500 Fluke DMM freshly calibrated. I am sorry to hear of the eye problems that “bwilliams60” is experiencing. Perhaps some medical help is required but I am not an optometrist.
Even in 2020, automotive modules do not use an internal ground buss bar, separating the path to ground to continue proper operation, increases the chance of not having to revert to a backup program upon a circuit failure.
Even small voltage drops through an “197 Peanut Bulb” when lite, is 0.250 of an amp. Voltage drop can easily be measured while not having 10-20 amps to be accurate. This is not a realistic example for low current circuits found everywhere on and vehicle as to save weight, 18 - 22 AWG or smaller wire is more common, while higher current devices are placed closer to the power source. A simple low current ground circuit is used as an input then the control model using a “Truth Table” denies or allows, let’s an enhanced mosfet is switched on to complete the task. I never told anyone to use the chassis, frame, engine as a ground path to battery negative. It is simple truths, decades old, that have to be observed to make sure the connections are good, same with the battery and even more importantly the alternator as it is both power and ground. I have started many vehicles, with a good temp battery loaner, used to start only, then drove it into shops service bay without a battery in it. (Note; Not recommended anymore)
I consider the subject completed as I prefer to compare Apples to Apples, not Apples to sterilized labs, PHD’s or anything without tires on it.
OUT!
 
I do not understand why some have a hard time grasping the concept of a dedicated vehicle sensor ground. It needs to be on the same level of ground as the controlling model is so the input signal is correct. It is a simple fact that reference low on this circuit has multiple wires, terminals and a return path to ground at the battery & alternator.
The ground reference is not critical in automotive because an analog sensor ground is usually Vcc/2. Op amps can;t reach ground and cannot reach Vcc of say 5V, so it makes sense to use the instantaneous value of Vcc/2 as the reference. youmight call the sensor 0-5V, but in reality it might be 0.1 to 4.9V if Vcc is 5V. If Vcc happens to be 5.1V, the values would be different for +-100% sensor output.
 

MaxHeadRoom

Joined Jul 18, 2013
23,141
I have heard that the reason the Brits drink warm beer is because they have Lucas refrigerators. I have not been able to verify that, though.
One of the sources of the idea that the British drank warm beer was that at the time US servicemen came to Britain, fridges in pubs were virtually nonexsistant.
Beer was mainly pulled from a barrel stored below in the Pub Cellar.
i.e.Pub Basement.
To the Yanks, this was Warm Beer! :rolleyes:
Max.
 

MisterBill2

Joined Jan 23, 2018
8,803
One of the sources of the idea that the British drank warm beer was that at the time US servicemen came to Britain, fridges in pubs were virtually nonexsistant.
Beer was mainly pulled from a barrel stored below in the Pub Cellar.
i.e.Pub Basement.
To the Yanks, this was Warm Beer! :rolleyes:
Max.
Max, I was here in 1988 and the war was long over. And the pub was not some small one out of the way, but across the road from the Birmingham airport. And the comment about warm beer and Lucas refrigerators came from an engineer at Austin Rover company. So things were different but the beer was not cold. Cool, but not cold.
 
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