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Topic: Working AmpMeter people chime in (Read 6588 times) previous topic - next topic

Working AmpMeter people chime in

Reply #30 –
The ammeter is a micro-volt meter that measures the voltage drop across the shunt wire.
The shunt is a known resistance and knowing the voltage drop, the current (amps) can be calculated.
The scale behind the meter needle is marked in the amps that the tiny micro-voltage represents.

If you ever hooked up an buttstuffog voltmeter backwards you know the needle pegs backwards.
The ammeter needle is centered when at zero volts so it can swing in either direction.
The polarity of the voltage dropped across the shunt depends on which direction the current is flowing.

I have simplified the diagram to show how it works.

I can't believe these ammeters didn't work when cars were built but I can believe a lot of them are broke after 20 years.
If you turn on the headlights with the engine off and the ammeter does not move to discharge, it's broke.

Working AmpMeter people chime in

Reply #31 –
But the TC is wired differently??? Your print is exactly what i said and how it should be hooked up. Not like the TC print whuich is rediculous. You need top monitor all the in and out current through the shunt. Bottom line is the ammeter is useless anyway. It should work for estedics i agree with that. but as a monitoring device it sucks big time
I spend money I don't have, To build  cars I don't need, To impress people I don't know

HAVE YOU DRIVEN A FORD LATELY!!

Working AmpMeter people chime in

Reply #32 –
Quote from: TOM Renzo;443974
But the TC is wired differently??? Your print is exactly what i said and how it should be hooked up. Not like the TC print whuich is rediculous. You need top monitor all the in and out current through the shunt. Bottom line is the ammeter is useless anyway. It should work for estedics i agree with that. but as a monitoring device it sucks big time
I used the same 97 TC diagram that Scott posted. I chopped the top part off to just show the black and white part of it and not the shades of gray.
The stuff at the top of the diagram is on the battery side of the shunt instead of on the load side. It is all the stuff they added for '87.
The ride control, ABS and IRCM. So when the alternator is carrying that load it will move the ammeter in the charge direction. Don't know how much of the load that amounts to.
But it's only meant to be an indication of whether  the charging system is working or not.

In the old days that shunt was built into the ammeter. They ran that heavy high current wire through the firewall to the dash ammeter.
No fuse or fuselink, none of that sissy safety stuff.

Working AmpMeter people chime in

Reply #33 –
You dont have to tell me about it. i know from many years of experience. Still want an AMMETER???? We did this car a few  years ago. And the customer wired it. OOPS!!!! Almost lost the car from a shorted alternator. never eliminate fuse links!! Note the heavy ammeter wiring. Chrysler uses a shunt meter in these early cars


I spend money I don't have, To build  cars I don't need, To impress people I don't know

HAVE YOU DRIVEN A FORD LATELY!!

Working AmpMeter people chime in

Reply #34 –
Here is the car we did it and it wins at every show it goes to. It is beautiful. The owner regrets that he did not let me do the wiring. Thank God he caught it in time

I spend money I don't have, To build  cars I don't need, To impress people I don't know

HAVE YOU DRIVEN A FORD LATELY!!
 

Working AmpMeter people chime in

Reply #35 –
Quote from: softtouch;443972
The ammeter is a micro-volt meter that measures the voltage


I can't believe these ammeters didn't work when cars were built but I can believe a lot of them are broke after 20 years.
.

that's what we are narrowing down now,,

for some reason I am coming up mathematically, with about 100millivolt, simulating a low battery and getting the math backwards  to watts. so I can find ohms

either way, next steps are for mason to continuity test from the instrument cluster all the way out to the engine bay

getting close to the culprit.

funny thing is an open to one side of the ammeter would actually cause this problem,,, if the yellow were still in play and still well protected / cad welded..