The Stovebolt Site Forums The Shop Area The Electrical Bay Ammeter Not Moving

Hi... I have a 1953 GMC 9300. I am having a problem with the Ammeter. It always sits just above the 0 on the charge side. It doesn't move either direction, when I pull the lights on without engine running, stays the same. Can run the battery down and it won't show a charge.
I have checked the generator for charge, it runs up to 14 volts at the regulator and battery when engine slightly sped up. Seems to be charging but not showing. I did a continuity test across the two terminals on the ammeter and have continuity. I hooked a leed to each terminal on the gauge and but a AAA battery to it, it moved a bit, then reversed polarity and it moved a little the other direction. I assumed it should have pinned to either side.Its a fairly new gauge but has never worked. Checked the wiring and seems okay.
Any ideas ??

Do you have a generator or an alternator? A 53 was manufactured with a 6 volt electrical system with a generator. Someone has obviously done some rewiring, and they might have bypassed the ammeter in the process. Some less than well-informed spark chasers believe that there's some sort of hazard involved in running the battery charge/discharge current through a dash-mounted ammeter.

A AAA battery, even at a dead short, won't have enough current capacity to deflect an ammeter more than a fraction of its full scale. You could try a D cell instead, but that's a really bad way to check things out.
Jerry

Thanks Jerry

It's a generator converted to 12 volt system...

The BAT terminal on the regulator goes to one terminal on the ammeter then to the starter switch and the other terminal goes to the ignition switch. From what I see in the wiring diagram it looks right although the diagram is for a 6 volt system, don't know if that makes any difference. Do you know of a better way to test the ammeter ?
Like I mentioned, the gauge is new but I just reconnected it the way the old one was. Perhaps there was nothing wrong with the one I replaced ?
Dave

If working correctly, your ammeter should have almost zero resistance from one terminal to the other (so the ammeter won't reduce the voltage of current flowing through it), so no...it wouldn't care about voltage. My observation has been normally the ammeter doesn't go bad, although the face of all gauges might look old. Some time ago I posted a free template for making waterslide decals and some instructions on how to do it. Should be around here somewhere although our tech-tips section hasn't been updated for a long time.

Here it is and there was a lot more to this in the original post:

https://www.stovebolt.com/ubbthread...52-gauge-decal-template.html#Post1398550

Thanks Jon G.
Should prove useful.

There's your problem. The BAT wire from the regulator should attach to the same leg of the ammeter as the supply wire to the ignition switch, along with the wires to the fuse block, if any, and the headlight switch. The only connection to the other ammeter post will be the wire to the starter. That way, current into and out of the battery must pass through the ammeter before going anywhere else. Turning the lights or the ignition on without the engine running will show a discharge since current is being drawn from the battery. Once the generator supplies all the current to ignition, lights, heater blower, etc. any excess current capacity will go to recharging the battery and the ammeter will deflect to the + side. If the ammeter goes toward + with the engine off and the lights, etc. on, swap the wires at the back of the ammeter.
Jerry

We had a similar problem with a "new" reproduction fuel gauge we installed in a '49 3100. The "exact fit" new gauge was almost .150" thicker. The needle was pushed against the face of the gauge by the chrome bezel. it was trapped and could not move.

Apparently this is not a new problem but the suppliers are not willing to fix it. The solution is to either grind/sand/file away some of the chrome bezel. Or just buy a NOS gauge like we did.

AD Fuel Gauge

All these problems go away with a 10si alternator ($50) and a voltmeter ($20). Can't understand why so many 12V converted hard heads want to fight this old dumb charging system in the name of "original". VERY false reasoning involved. So easy to clean it all up. Gets rid of all those wires, the voltage regulator, connectors, using the ammeter as a power junction, contacts, brushes, hard to find parts, extensive troubleshooting. Lack of reliability. Cost of converting a generator. Folks want to convert to modern 12V, radial tires, upgrade brakes, steering, new wiring harness and all that kind of stuff and then want to keep generator, VR and ammeter?????

If they have trouble, someone has to explain the whole world of electrons to them and 15 different tests which they don't understand. Let er' rip.

The ammeter will not cause a fire.