Ammeter Problems/Questions

-
W

whitey

Well-Known Member
Joined
May 26, 2004
Messages
753
Reaction score
5
Location
Andreas, Pa (near Allent
On my way back from Carlisle the Ammeter in my 73 Dart was pegged, turning brown (I have white face overlays) and smoke had emitted from the gauge. I had it roll-backed home and now have the windshield out, and pulled the dash frame so I could examine the harness easier as a whole.

I found the red and black wires connected to the ammeter are fried from about an inch and a half before up to the gauge, the leads on the gauge are fried, the circuit board is discolored, and the light bulb plug is melted with the bulb discolored.

I have a circuit board and Ammeter from a 71 Duster that is in pretty good shape, but I was wondering what could have caused this and if there is some way to correct it or bypass the ammeter and would I definitely have to have a voltmeter?
 
Here's an awesome article about this very issue:

I wouldn't put it back together till you read it.

http://www.madelectrical.com/electricaltech/amp-gauges.shtml

It discusses the problem and tells how to implement a solution. I'd run a voltmeter if the car gets driven a lot. I wouldn't do anything till you either perform the fix or figure out the problem or you'll probably smoke the gauge again.

Good luck!

Steve
 
" Light bulb plug melted " part is a puzzle to me. The amp gauge is mounted clear though the housing and not actually connected to the printed circuit board. I suppose the heat from the gauge and wires could transfer to surrounding parts.
You can use a 10-24 nut and bolt to lug the red and black wires together. The fusible link should have been the weakest link and burned open but it didn't. The weakest link was your amp gauge but it wasn't nessesarily the initial problem. I would check the bulkhead connections etc.. for a short circuit. I can't guarentee there is another fault that you haven't discovered yet but it is highly possible.
 
Typical failure mode for ammeters. There are those that have, and those that will. A 10 AWG wire from the alternator directly to the positive battery cable takes the charging load out of the instrument cluster and the bulkhead connector.
 
I concur with the madelectrical article. Besides, the voltmeter tells me more useful information than does the ammeter.
 
if water got onto the bulk head connector could it cause this problem , since we did have the down pours on the way to carlisle?
 
generaljmwlee said:
if water got onto the bulk head connector could it cause this problem , since we did have the down pours on the way to carlisle?
Click to expand...

Water is conductive and anything is possible but... these cars have been driven in the rain for over 30 years. A more likely senerio would be water inside the car, on the fusebox, headlight switch, etc..
 
I don't beleive this was a water leak problem. I have done research and have read articles on the higher amperage alternators just putting out more and the ammeter being the weakest point. Judging from how the wires are melted, the circuit board is toasted and the bulb socket melted a bit, there was some serious heat there. even the back of my aftermarket tach is distorted

http://www.allpar.com/history/mopar/electrical.html

http://www.allpar.com/forums/index.php?showtopic=52757

http://www.moparaction.com/tech/quest/FRIED_ELECTRONS.html

http://www.allpar.com/fix/alternator.html
 
What people dont understand is an altenator cabile of producing a million amps will only supply what is called for.
I understand that any gauge can fail. I also understand that resistance creates heat, not amps. That point where the weakest components create the most resistance will melt down first. That point is not nessesarily the root of the problem in every case. Good luck
 
You must log in or register to reply here.
-

Back
Top