C2 ammeter

[Dan Tewell]

Help! I've got a 65 on which I just had the gague cluster restored. The ammeter doesn't work. I've disconnected the plug on the gague and checked for voltage on the wires. Both of them show battery voltage. After searching on this board, I checked for resistance across the gague (with the wires disconnected) I got a reading of 0.00 milliohms. Somewhere on here someone stated that it should be approx. 500 milliohms. I checked this against my 67 (whose ammeter works) and got the same results. What gives? Is there any other thing to check? I've got this bad feeling that the gague is bad and I'll be pulling the cluster again.
Dan

[Gary Cederman]

Re: C2 ammeter

Dan,

I am not sure what to make of the "0.00 milliohms" except if you are getting the same reading on a good ammeter then I would think that the ohmmeter is unable to accurately read that low of a resistance.

Did you confirm that the ground wire for the cluster is connected? The ammeter circuit requires the two power connectors and the ground connector. I don't know where this connector is on a '65 but, on a '63 there is a spade lug that is held down by one of the meter housing screws. The ground connector is attached to this lug.

Good Luck,

Gary

[William C.]

Re: C2 ammeter

you can check the meter using a 1.5 volt flashlight battery, just touch the terminals of the ammeter with the 1.5 volts and you will get an immediate full scale deflection. Don't wait to admire it, all you need is a "flash" connection to see if the meter is working, too long a test will hurt the gauge. If the meter is working, the usual culprit is the quality of the connection behind the fuseblock into the engine compartment. The meter actually works as a sensitive voltmeter, reading the voltage drop at both ends of a wire in the engine compartment. It only takes a small amount of resistance at the connection in the engine compartment to screw up the reading.

[Dan Tewell]

Re: C2 ammeter

Bill, Gary,
Thanks for the input.
Gary, I think that the ground lug on the 65 is a spade connector at the top of the cluster. I'll check that it is instaslled, although all the rest of the gauges work fine. Don't they also need this common? ground?
Bill, I assume that if I try the battery trick and it doesn't move, that means that the gauge is bad?
I'll give it a try today.
Thanks all, Dan

[William C.]

Re: C2 ammeter

No Movement means the gauge is bad. By the way, it can be removed with patience from underneath without pulling the cluster

[Gary Cederman]

Re: C2 ammeter

Dan,

You are correct that the fuel and temperature gages do require the ground.

The reason for suggesting the ground as the problem is becuase you stated that you measured battery voltage at both terminals going to the ammeter and that your measurement of 0.00 milliohms was because of the ohm meter, and you didn't mentioned whether that the other gages worked or not so, I thought that the only thinkg left is the ground.

Anyway, Bill's suggestion of the 1.5 battery test may work, my only problem with that is if you tapped the 1.5 battery too long (what's too long?) it will blow the coil wire in the ammeter then you are S.O.L.). So, be careful.

Gary

[Scott Butville]

Re: C2 ammeter

The ammeter will work hanging by the wires under the dash, no ground is required. If you have another, just pull the connector off the one in the cluster to check it out.

[Dan Tewell]

Re: C2 ammeter

Thanks Bill, Gary and Scott. I checked today with a weak 1.5 volt battery. The needle didn't even flinch! I put in a call to Corvette Instruments as they just did the cluster for me. I was hopping that it would be something simple that I could fix, but it looks like it'll have to come out and go back.
Thanks all. Dan