Patient = 1977 F-250
Disease = Ammeter not showing charge or discharge
Symptoms = Shows charging at battery, but not at dash gauge

Where do I start checking?

Also, temp and oil pressure gauges appear to be reading low too. Would dash voltage regulator have any effect on these?

Thanks all.

 

What is your expectation of the amp gauge? Even when they are functional, the movement is barely discernible...

 

Well, kind of expecting it to do its job...show me how much its charging, or discharging. My old '78 S/Cab's gauge worked just fine. Just want this this one to function like that one.

 

I understand you want it to work, but (judging by the four I've had) even when they are working, there's not much movement. The only time I see any of mine move is when I turn on the headlights-they dip just a hair towards the big D

Unlike the voltage gauge I have in the copper truck, there's no big "swing"

If you're looking for a lot of movement to convince you that's it's functionong, you're not likely to see it. In my experience

 

^^^ Concur with Padre Ursus arctos de Yuma.

To me the ammeter is pretty much a useless gauge.... I totally prefer a voltmeter.

 

I added live gauges to my truck. I know its not all original but I like reliability and accuracy. Those ammeters were not of much use when the truck was new.

 

I vote the same as the other guys. I put a volt gauge in my truck left the amp gauge hooked up. The volt gauge shows different reading for different things going on in the truck. Amp barely moves any maybe.

 

Innova makes a pretty slick voltmeter display for under 10 clams that plugs into the cigarette lighter receptacle.

 

Mine are reading a little funny, too, there are a few suggestions to check in this thread -

https://www.ford-trucks.com/forums/1...-question.html

But as far as the ammeter function, it's that same weirdo shunt-style, and none of mine seem to work great - always figured that's just the way they were, wish they'd have used a voltmeter instead. 2 of my fleet had been hacked on by the PO - both looked like they'd been a little hot and some point, and got "re-wired" with whatever was handy. I ended up with 3G's on both of those (both needed more juice than the stock 65 amps), and that alone means the ammeter gets sorta bypassed. All the connections for the shunt are in that factory taped-up doubled-back mass of stuff coming off the alternator up to the regulator, it would be worth peeling it back and seeing if it's still even hooked up.

 

Cougar Innovations makes a direct replacement voltmeter in place of the stock ammeter. I agree the ammeter is useless

 

If you do this it will change your ammeter to a voltmeter and utilize the same place in your dash. There is a choice of scales and the needle moves a lot. The cost is reasonable. I've done it and like it.

Rocketman's Classic Cougar Innovations

 

That's a pretty cool idea to keep the factory gauge but actually have it function. I might consider it...

 

Thanks for the heads up on the Volt Meters. I never liked my Amp meter because it is pretty well useless. Will be ordering one for mine from Cougar Innovations.

 

Rocketman's Classic Cougar Innovations

 

OK...that sounds plausible for the ammeter. I like that voltmeter conversion idea. Now, any idea why my oil pressure and temp gauges read low as well? I have replaced the oil pressure sender 3 times...same readings(engine is new and I know it has good pressure)....replaced thermostat with new 180*, needle barely moves even when engine warm (thermometer in top tank reads 180* when warm). The fuel gauge seems to be accurate.