Author Topic: Amp Gauge 69 Camaro  (Read 8118 times)

montgomg

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Amp Gauge 69 Camaro
« on: June 28, 2012, 01:12:43 PM »
My amp gauge does not work. Needle stays at O at all times. Alternator is charging, battery is at 14.5 Volts with engine running.
I have checked continuity on the red wire running from the horn relay to the terminal behind the battery. It is fine. I have checked the continuity of the wires (black and black with white stripe) at the console plug in (at the 10 or so pin console connector).
I have continuity on both the console side of the connector and the firewall side of the connector. I have run a separate ground from the amp gauge to ground with no positive results.
My service manual does not help me trouble shoot at all.
I think I have continuity to the console plug in telling me the fusible links are intact. I am not so sure about my tests on the gauge itself. Any suggestions would be appreciated. I have read the many threads both on here as well as on Team Camaro but am now stumped!

montgomg

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Re: Amp Gauge 69 Camaro
« Reply #1 on: June 28, 2012, 02:34:37 PM »
Should mention that when checking across the terminals on the back of the amp gauge with my multi meter I get a reading of about .4 Ohms. This is with the battery disconnected and the console connector unplugged.

Mark

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Re: Amp Gauge 69 Camaro
« Reply #2 on: June 28, 2012, 04:00:38 PM »
there is no ground needed on the stock console "ammeter".  It is really a -0.5 to +0.5 range millivoltmeter labeled in Amps.  It uses the resitatnce of the red charging wire that runs between the horn relay and the battery to provide the voltage drop to deflect the needle.  When the battery voltage is higher than the horn relay terminal voltage the needle deflects down scale towards discharge, when the horn relay volatge is higher than the battery voltage the needle deflects upscale towards charge.  thats all there is to it. 

If you tried to run anykind of current thru it, like grounding either end of the black, or black with white trace wire, while the other is still connected, you ran 12V thru a 1V range meter and probably smoked it. 
It doens't take alot of current to burn up the wiring in the gauge itself.  If you've replaced the red wire that runs across the radiator support from the horn relay to the battery terminal with a large size wire the gauge may not even register the difference and will sit at the 0 point all the time because the voltage difference across that wire for normal charge or discharge currents is no longer high enough.  Do not under any circumstances try to run current thru the gauge, or attach anything to the circuit higher than 1V DC, you will be buying a new gauge if you do that.

Measure battery voltages at the console connector on the black and black/w wires.  You should see battery voltage on both, if not the wires are open somewhere.
Mark C.
1969 Indy Pace Car
350/300HP RPO Z11

montgomg

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Re: Amp Gauge 69 Camaro
« Reply #3 on: June 28, 2012, 10:10:41 PM »
 Thanks for responding.
  I did find a thread of yours on Team Camaro which outlined how to test the amp meter with a multimeter using volts. I did so and the amp gauge tested good.
  I noticed a slight amount of corrosion on the two terminals of the amp gauge. Upon cleaning those thoroughly I am now getting some needle movement. Might have been just enough resistance on the corroded terminals to render the gauge dead. I may be out of the woods on this item now. thanks again.