BB wowbagger

Those two smaller wires that connect to the side of the Alt,whats up with those?
I know that one of the wires are for the Field (F) and the other one is marked "R" on the Alternator.Whats "R"?
I checked my wireingdiagram and the Brown wire is connected to the Lightswitch to "start" the Alternator and the White/black giong to the Ampmeter/hornrelay.
As i searched the archives everyone seem to say that the Black/white wire should be connected to the F on the alternator?That would mean that theres always 12V on that terminal?
On the Wireing diagram (Lectric Ltd) says that the letter on the Alt should be "V" and "L",but i have "F" and "R".Not original Alt?
What happens if you switch those wires?
The reason i ask this is that it seems that my alternator doesnt seem to charge the battery and i noticed that my Ampmeter is dead,it doesnt move at all.
Its a 73
:cheers: :smash: :cool:

mrvette

BBw. you can switch the wires and the net effect will be zilch, as long as everything is working correctly, where the problem would come in..is if the alt quits for any reason, and the unit will then attempt to turn on a 'light' which in this case is a piece of resistance wire, the brown one, taking place of the typical dash idiot light, you are correct, the black/wh wire is going through the ampmeter to the wiring harness allways positive, unswitched...

viewed from the back of the alt....the brown wire goes to the FIRST terminal viewed from clockwise direction....the bk/wh wire goes to the second terminal....

GENE

BB wowbagger

So theres no way to tell on a,for example a 73,that the alternator has gone bad?Should the Ammeter drop?
I just cant fifure out why my Ammeter doesnt move.I measured it with a Multimeter and it has some resistance,so it doesnt appear to be broke..

mrvette

Without snowballing you with a bunch of theory to confuse your issue, in fact an ampmeter is nearly useless, and in fact the way these modern ampmeters are hooked in series with the alt SENSE wire, they are nearly useless....the indication that anything is rong with the electrical system is tenuous at best...hard to see/impossible to see at worst...not at a glance anyway...
so that is why later cars went to voltmeters....
at any rate, with the correct hookup, the ampmeter should swing with the immediate charge rate of the battery, and deflect a bit when say light or heater blower are turned on....it's rarely if ever a very large swing....

the idiot light is missing and substituted for a resistance wire instead...but I put an idiot light under my hood on my wiring,...so the damn thing lights up if the alt is not charging, engine running....I use a voltmeter out of a mid-late 80
's chebby pickup....works fine....allmost a direct swap...just hood the two wires together, and find a SWITCHED +12 and of course suitable ground, and the changeover is complete....

GENE

BB wowbagger

Whats the purpose of the resistancewire? Why not a "normal" wire? :smash:
Any thought on why the letters on the Alt is different from the Diagram?
:cheers:

mrvette

Personally, I have never seen two alternators alike in that regulator marking department....some are A-B, some R-F , some 1-2 hard to say what was on their minds when casting the things....some of them said nothing who knows who made what and when.....cars this old, anything goes....

the brown resistance wire was some smarty pants EE's answer to NOT including a red idiot light in the vettes of our vintage....so the newer alternators needed that light as a source of triggering the regulator on correctly, so you need not rev the engine to 2-3 grand in order to get the damn alternator to start charging....and if you have a ~600 rpm idle, sometimes without that idiot light hooked up, it would go to discharge, and another trip to 3 grand was necessary to get it to charge again....I dunno why, just is.....my experiences and test anyway.....

I been fighting these alternators on and off for a long time over several cars ranging though the 70's and 60's even, and even on boats, wondering what in hell is going on with all these crazy 'one wire' and hi amp units, and so forth...well, one afternoon about ten years ago I decided to sit down, or bend over the engine long enough to figger out just what in hell was going on...and so that is where I know them well enough ......course being an ET background helped a LOT, but you know, those diagrams are confusing as hell when printed on 8x11 pages, I need D size drawings to make sense of most anything these daze.....

GENE

BB wowbagger

If i were to connect a Idiotlight to my Alt,can i use the Brownwire for that or do i have to rewire the Alt harness?
:smash: :cheers:

mrvette

BBw, I don't recall the diagram all that well, except it's final resolution but it's my recollection the brown wire itself is the resistance wire maybe the same type wire as going to a breaker points distributor but not sure of that....

all I did was rewire the car to do it my way, previously on that '70..Lemans/GTO and then on this '72 vette...hung the light near the horn relay under the hood...since if the voltmeter was low, all I needed was a light to tell me if the alt was dead or not....in fact I know that allready, but the lamp is in the circuit to allow LO RPM charging.....

GENE

BB wowbagger

Whan i was in the garage today i started to trace the wires to the Ampmeter and i think i figured out why i didnt move.I had connected both the Black/white and the Black wire from the Ampmeter to the hornrelay.
As i have understood,the Black wire from the Ampmeter should be connected to the starter to measure the differens between the two points?
I also got my hands on a Voltmeter that i will connect to check if the Alternator is working.
Does the Voltmeter from a newer vette fit the consol on my -73? :smash: :cheers:

mrvette

NO, the newer vette voltmeters are flat on the bottom, so look weird in our early shark cars....the one you need has slightly differant printing work on the face, but it's a direct bolt in, and IMO looks fine...takes a detective to spot it ......

Well I can't tell you about what is rong with your wiring....not from 3K miles away, anyhow....

however the essentials are that the black wire TO the voltmeter I THINK comes from a fixed--allways ON source....and the black/wh trace wire goes to the alt regulator imput.....so you see that IF these two wires are reversed in fact if everything is ok, the cars runs fine,....UNLESS you reverse them, THEN IF you have an actual ALT/BAT/GEN red lamp lenz on the dash panel, the light glows dimly mostly seen at night of course, and so that is what prompted my exploration of the situation causing that....but having NO wiring diagram to the old Pontiac Lemand/GTO giving the symptom, I had to dope it out myself...finding the wiring error done by I THINK a previous owner....but maybe me, as I could have been in a hurry....too many years...can't remember...

but at any rate the wiring is stated fairly clearly, and the reasons for resistance 'mystery' wiring have been explained...and so I still have an 'idiot' light hanging under my hood near the horn relay, and WTF, it WORKS!!!

MY car is a hotrod anyway, totally suited to MY body, and other performance requirements....I suppose the only people to come close to my mods list are Norval, TT, Monte, and so forth...not that I have done what they did to the exetnt they did in any field....but did within my budget the same sorts of things....left NO stone unturned....

freaking cars are an obsession....

GENE

REJ

I think, i got that brown wire, and the black/white wire on my 72 vette alternator figured out. / the brown wire, goes to the first terminal (left), and the black/white wire goes to the second terminal (right)....viewing this from the back of the alternator....(clockwise).....will see...thanks..bob from fl.

lvmyvt76

you are looking at a 13 year old post