My Ammeter Doesn't Work

[cgrossl]

All of the gauges in my 72 work fine, except for the Ammeter. Its not that big of a deal, but I would like for it to work. Are there any simple things that I can look for that might fix it? Is there a way to test the gauge?

[byrd]

look under your hood on the drivers side by in the front corner and look a football looking black in line fuse holder, and there is another one like it near the battery on the passengerside. that is what I would check first, and the fuse shoukd be 3-5 amp...Randy

[4tiresngas]

Cameron, I have the same problem. Both my fuses are brand new. The entire wiring harness is brand new, but the needle on the amp gauge doesn't even hint at moving when I turn the key.

If someone knows how to bench test gauges...Amp, Temp, and the like, that would be awesome.

[neonlarry]

Might check out this site:
http://www.fix-a-gauge.com/

[4tiresngas]

Thanks NeonLarry. I ordered the amp and temp gauge kits. It was only $18 with shipping. So, hopefully that will square me away on those two.

[Mongo]

Originally Posted by 4tiresngas

Thanks NeonLarry. I ordered the amp and temp gauge kits. It was only $18 with shipping. So, hopefully that will square me away on those two.

Let us know if they are worh anything. I for one like to see pictires of what I am buying.

[byrd]

I use them all the time and I really like the resistors they sell. I haven't used one of their ammeter kits, haven't needed any just my .02 Randy

[louaxtjr]

Really appreciate you guys. Found this thread using Google and the fuses were not present in my truck. 5 minute fix and my ammeter is working for the first time in 2 years!
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[VetteVet]

The ammeters in our trucks are external shunt types so in order for them to work there has to be a shunt in the wiring between the battery and the alternator. If you rewire the truck and wire the alternator output wire to the starter or the battery you will have eliminated the external shunt and the ammeter will not work.

The external shunt is nothing more than a 12 gauge wire between the right fender terminal post and the alternator regulator battery junction in the left side harness.

Here are 2 pictures to illustrate this.

This is the shunt wiring and the fuses are circled in red.



Here is the joint on my 67. It's the red wires.

[72 K20]

I've owned all together, past and present 8 of these old trucks and never had an ammeter work until I was informed about these fuses and the role they play. 3 of the 4 I have now have working ammeters. The 4th truck is for parts.

[73CheyenneSuper20]

Worked for me! Replaced both fuses- one was broken, other fell apart, reconnected wire, my gauge works! That was the only gauge not working, I hadn't gotten around to figuring out why until I found this thread.
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[shawno72]

Ok guys how about this? I converted my truck from idiot lights to gauges. Installed the fuses and my amp meter gauge worked great. Well I upgraded my old tired looking gauges with some nos units and now the amp gauge has zero movement. Checked fuses and fuses are good, bad gauge maybe? Whats your guys thoughts?
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[jjzepplin]

I have a one wire alternator and no regulator. Should my gauge still function?

[48richard]

I have an internally-regulated alternator, and the ammeter does work, but the needle deflection is very small. For example, with the headlights on and the A/C blower on high speed (engine not running), the tip of the needle only moves about 1/8" to the left. Is this normal?