Doing contract work now so I have more time than I had before...and nitpicking.
When I originally did the 3G swap, my charge/discharge gauge stopped working and I don't know if its expected. Did I neglect to hook up a wire, kill the gauge, or do I need to change something on the back of the cluster to get this gauge back? Ideas?
Next on the list: make girlfriend try reupholstering a spare seat.
I cant believe coolcats.net does not have a template for the 3g upgrade yet,,,unless i missed it somewhere,,,ERIC?
anyway,, i dont remember anyone here ever having to modify the cluster for a 3g alt upgrade.
It's common for the AMP gauge to stop working with the 3G swap, but it's even more common for it to just not work anyway. Why the Mustang got a volt meter while we got an AMP gauge is beyond me...
Guess thats all I needed to know. Its 'common' though or always happens? Mine didn't work for the longest time, then one day I took it out for whatever reason, and it worked again when reinstalled. After the 3G, its never budged. I'm assuming, since its an amp gauge and the 3G puts out more current, that its just completely incompatible.
Like Thunderchicken said the fact an amp gauge ever even worked in one of our cars is more the oddity than anything. I think most of us who want a reliable gauge installed an aftermarket voltmeter. The voltmeter also provides more useable info than a amp meter.
Since all the gauges in the buttstuffog cluster could be considered marginally accurate at best many have actually opted for the volt oil temp combo, and installed them in the center stack.
actually, the ammeter isnt reading amps at all. It reads a voltage drop across a calibrated length of wire or some other component that also has a specific resistance. This is called a "shunt". It could be a resistor or a wire length but nevertheless, it is a part that has known values of resistance and temperature coeficient.
The ammeter just wires up on either side of the shunt and feels the voltage drop across the shunt. The voltage drop is usually in the milivolts range and that potential is displayed by the needle movement. Now all the engineers had to do was stamp the face of the ammeter guage with markings to interpert this into a display that shows amps.
This is basically how all ammeters work, there really isnt an ammeter out there that reads only amps by acually doing the task of absorbing and displaying amps. If this were the case, your cluster would get 100 times hotter than normal imho.
Its resonable that if you change the power source in the slightest way that the ever so sensitive ammeters basline for what is considered a "known" or "standard" charge would be adversly effected by a drastic upgrade like this.
No I don't...because a simple trip to a search engine yields the same info I'd offer, on other sites.
If you are adventurous you could remove the cluster and inspect the amp gauge. Inside there are two thin wires that should not be touching. If they are, push them apart then reinstall and see if that helps. If they aren't...well, it's just the nature of that gauge unfortunately. The NATO guys often talk about that gauge...I bet 75% of them don't work. But those that do, work ALL the time. It's like an on-off switch for reliability.
The one on my full digi dash works. It moves up and down based on electrical load. I've never seen a full digi dash where it didn't work. Do you have the standard cluster? Maybe the digi dash just lies. I have no idea what each bar means anyways:grinno:
Heh . . mine's a classic case then. Needle's always just a hair above the middle, regardless of revving, idling, or even with the car shut off and the headlights turned on or off... never budges!
Interestingly enough, the AMP gauge on my 1970 Chrysler and 1974 Dodge a few years back always worked. The latter was particularly useful for letting me know when the voltage regulator gave up the ghost . . a brief surge with the needle going almost all the way to C before falling down dead at the D and not budging again. Er, 'til I changed that regulator, anyway.
What the heck causes these things to fail though? I'm guessing it's not simply a case of a loose wire?
Thunderjet302: The full digi gauge is a volt meter, not an ammeter. They always seem to work.
King V: I dunno about the '74, but chances are the regulator in the '70 is mechanical, so it likely just wears out
Erm, actually what I meant was, what causes the AMP gauges on the Fox cars to go bad. I'm guessing what caused my 74 Dodge's regulator to go was the fact that it was about 20 years old at the time!
If I crank the radio for a while with the car off, then start the car, the gauge will be about 1/4 of the way up the charge side.
Doh I thought we were talking about volt meters. I need to read the posts more carefully :dunce:
The ammeters generally fail due to the horseshoe magnet inside the gage loosing it's strength... Rarely have I seen one that actually worked(and I've owned 14 '87-'88 TCs). A couple years ago I played around with a large magnet and sorta reenergized the magnet in one. It would deflect to approx the mid point(of charge) on startup, then fall back to the center as it should. Also would drop into the discharge with lights and accesories on with the engine off.
When you add a additional wire back to the battery from the alt(3G swap), you are creating a parallel path for the current, so the gage will never work again reguardless of cond...