From the meter:
One wire eventually ends up at the battery terminal on the solenoid.
The other wire eventually ends up at the alternator.
Is it true that at the meter, the two wires are not connected and one wire connects to each meter terminal?

 

Who really cares?

Since you think the wires should be shorted why don't you at least give 1 positive benefit that is gained by shorting the wires instead of leaving them disconnected.


No-one posted that the dash ammeter measures battery voltage.

 

You're correct. Who cares about how these car's electrical systems operate?

 

As I already posted, the meter is calibrated to have a certain needle movement based on the voltage applied between the terminals. Claiming that it's an ammeter because current in the coil is what causes the meter to move is simply a ridiculous semantics argument.

Here's an example of what GM would have done to design the ammeter circuit. Say they know the length of the 10 gauge power wire they are connecting the ammeter across is 3'. They would then take the resistance of 10 gauge wire and calculate the voltage drop with 1A of current flowing. The number is approximately 3mV. So, they get the meter manufactured by specifying 3mV/A for the meter movement (ie 3mV causes 1A to be displayed or 30mV = 10A, 90mV = 30A etc). Now, if there is 15A of current flowing in the 3ft piece of 10 gauge wire there is a 45mV drop in the wire. The meter measures the 45mV drop across the piece of wire and deflects to 15A on it's scale.

This is all nice to know but none of the above helps the OP with his answer. Remove the meter and the wires are not required. Connecting them together may not cause an issue today, but it serves no purpose. However, if the main charging wire is interrupted or has a bad connection down the road those small meter wires will attempt to carry the current and a failure will occur. Hopefully, just the fusible links but something worse could happen.

So yet again I will ask - Post 1 advantage gained by connecting the wires together?

If there is no advantage then why should anyone do it?

 

The OTHER end of the meter wires connect to the same terminal at the horn relay, why it that different from connecting them at the meter?

 

No, they do not. 1 wire goes to the horn relay and the other wire goes to a junction with a piece of 10 gauge wire between these 2 points. If you connect the light gauge meter wires together and the 10 gauge wire fails, the current will pass through the meter wires until a fusible link blows or the car catches fire.

 

OK thanks for clearing that up.
I just didn't see that on the schematic.

 

The above description of the "ammeter" is correct. It is a millivolt meter reading the voltage drop across 2-3 feet of heavy gauge wire and converted to AMPS on the meter scale.

The VOLTMETER that is included with later C3 cars reads battery voltage directly, so it's not the same meter nor wiring as the AMMETER in the earlier C3 cars.

One more time: If you were to connect the two ammeter leads together, those two leads would then become (electrically) an alternate path (parallel to) the main power wire in the harness. That means that both that main power wire AND the connected leads will be trying to carry the total current load for the car. The resistance of the small wire leads will be a bit more than the larger wire; but it will still be very low and will still try to carry somewhat less than ONE-HALF of all the current sent through that (now, THOSE) wires. So, when the battery is being charged at 40-50 amps, nearly half of that will be sent through those two, small awg wires.

Can anyone guess how long 25 amps through a #14 awg wire will last?

How about having that wire running through your dash while heating at 25 amps? If lucky, one of the fusible-links will fry before that wire. If not, well......

Why is this so hard for folks to understand???

TAPE THE DAMN LEADS OFF AND DON'T CONNECT THEM!!!!

 

If there is 25 amps flowing thru this #16 (not #14) wire connected to the ammeter, why don't the two fusible links burn? This circuit is protected by links at both ends because both ends are subject to high amperage (battery and alternator) and GM didn't want electrical fires in case of a short circuit. As a matter of fact, the meter itself is a fusible link-ask anyone who has fried his ammeter. The meter melts before the links do. The links themselves have a measurable resistance-that's why they heat and melt. Every other circuit in the car is protected by fuses or fusible links. I think that the engineers at GM had at least a fair understanding of what they were doing. The bottom line is this, there isn't a voltage divider resistor in series with the meter. It is installed as an ammeter, and has nil resistance, and for all practicable purposes is a short circuit.

 

Agreed!


The bottom line is that you don't know what you are talking about. The movement of the meter is built to measure a voltage. It may be a small voltage, but the meter is actually measuring voltage non the less.

You starting posting this crap to try and backup your claim that it is fine to short the wires yet you have still not provided one advantage gained by shorting the wires....

 

First of all, I never said there was an advantage to connecting the two wires. I said that you could, but it isn't necessary.
Second, analog meters all read current flow, not voltage. attach one lead from a meter to the horn relay, and nothing registers until current flows by grounding the other lead.
Thirdly, I give up. There are some things you can't fight.

 

OK..so basically if I am using an extension cord in my garage- I should unplug it IF I am not using it- because something might happen to it???

lionelhutz-

You missed your calling as a defense attorney....

Never-mind- I Googled your screen name...Got it!

 

Well why would you if there are no advantages?


You aren't being clear but it seems you keep making this claim about the meter movement specifically. All analog meter movements for voltage or current measurements are calibrated to deflect a certain amount due to an applied voltage.

You connect the meter movement to a shunt which gives a certain voltage for a certain current flow to make an ammeter.

You connect the meter movement into a voltage divider network to make a voltage meter. Actually, you can build a meter so it can be connected directly.

In both cases, the meter movement itself is based on the applied voltage.

You're confusing the fact that it is current which causes the needle to move with the overall design of the meter which is to deflect based on voltage.

 

I'm not sure why you would even bring this up. What does it have to do with the topic? However, most people have never seen an extension cord arc at the female plug. If they did, they wouldn't be so cavalier about just leaving cords lying around still plugged in.

 

Some folks just want to argue and have no interest in learning. Some folks, you just can't help....

 

I agree!
BTW, I dug a ammeter from a 72 out of my storage and measured the resistance. It was less that 0.1 ohms. It's an older Fluke 177, so it's not up to NASA standards, but it's pretty close.

 

Ya...

Not having resistors doesn't mean the meter has to be measuring current. I can show you industrial panel meter catalogs filled with meters to measure AC or DC voltages up to around 250V with no voltage divider resistors. The catalogs also contain ammeters to use with external shunts and the meter standard is 50mV moves the meter to full-scale on the dial.

The divider resistors were often found in analog multimeters. The range switch changed the resistors to allow having different voltage ranges on the meter.

 

There must be a load or resistor that causes a potential (voltage) difference. If test leads are placed on a conductor a short distance apart there will not be a voltage difference because there isn't a measurable resistance between the leads, regardless of what the supply voltage is. This is the case on a 250 volt industrial power supply or a 250,000 volt high tension line. Don't argue with me, argue with Ohms Law.

 

Huh??? You have apparently switched to writing about superconductors?????

A piece of typical copper wire has resistance. When current flows, there is a voltage drop along the wire, even if it's just a small voltage. The meter measures this small voltage drop. Nothing about how this meter works is breaking Ohms law.

 

Huh??? "short distance" and "measurable"? What's the resistance of one foot of #10 copper wire at STP? It's 0.001 ohms-I can't measure that. It would take 1000 amps to cause a one volt drop. And you're not going to get #10 wire to carry 1000 amps.