My alternator 1 wire or 2?

[Oldtimer]

Is this wire also connected to the battery side of starter relay?
It looks like the Black wire that should come from the ammeter.

Do the rear tail lights and the front parking lights (not turn signals) work? This would mean that there is power to headlight switch and it is working. If tail/parking lights work, but headlights don't work, take a look at the dimmer switch, on the floor below the parking brake pedal.

 

[EPB72]

I didn’t recognize that model Alternator either at first. But looking at the backside of the pulley in the first picture made it immediately apparent that it was GM-based (12si?) alternator.
At least, as far as I remember, other manufacturers didn’t use that style.

Looking at the new picture just confirms it. That pulley started in the 70s and ran through the 80s I believe. Maybe even the 90s now that I think of it, because I believe my 96 had that style pulley.

Many modern internal regulator alternators do not have an external stator post. Some, like a Ford 3G, do have one. But I don’t know if it’s able to be used for the same thing, since none of them ever came on carbureted vehicles that I’m aware of.
You’ll have to look up that model and see if there’s anything available for that. Otherwise I guess you’ll just have to use switched 12 V.
Anybody know whether or not that would mess up a factory choke?

Yep . GM and on Cadi deville,sevilles eldos.. with the style connector I'd say late 90"s {97-99} ? would be rated in the 140 amp range..To the OP if the charge wire is not fused doing so would be best .

 

[Oldtimer]

Your engine harness may not be original (?), but these are the colors on stock harness.
RD/GN to coil
WH/RD to oil pressure sender
RD/WH to temp sender


. . . but only two make it out at the other end. . .
You can pull the split loom off the harness to find the 3rd wire.




This looks like the RD/GN wire that would have been connected to coil +.
It should be powered with key in ON position. If it is not connected, make sure to insulate it.

 

[Soylent]

@Oldtimer yes I found the red with white wire coming out of the plastic cover half way down the intake and is connected to the temp sensor


The black with green is currently connected to positive side of coil. The wh with red is loose and should go to oil pressure. My oil pressure standoff is currently capped off.

 

[Soylent]

@EPB72 Yes. I remember cadillac for some reason when the mechanic installed it 5 years ago but I thought that couldn’t be right. Maybe a jeep thing as that it what he has built for years. Which wire are you suggesting be fused? The smallvexciter wire or the 2 gauge battery line?

 

[DirtDonk]

The charge wire is the big battery output wire. In this case your two gauge cable.
The two most common types of fuse for use here are mega fuses, and midi fuses.
Something slightly larger than the rated output of the alternator. So if it’s 70 A, a 100 amp fuse would be typical. If it’s 140 amp, 175 amp use would be typical.

 

[Soylent]

Ok. I see those on Amazon with the fastronic or painless holder. I need to confirm what amperage the alternator is. Any need to fuse the wire from battery to starter? Or no because that isn’t an overcharging situation?

 

[DirtDonk]

Correct. No fuse on starter cables.
Amperage varies, and probably because nothing else is effected by a melted starter cable.
Usually…

Can you still contact the installer?
If not, look for any identifying numbers printed, or stamped on the alternator.
In lieu of those, a testing machine at your local parts store can probably determine output.

Was it in this thread that you mentioned 72a? Or am I thinking of another discussion?
That 72 is a good common number, but does not guarantee that you have one.
If it’s just 72, there’s no reason for the big cable. Doesn’t hurt anything, but isn’t needed. So wondering why they installed such a big cable unless they had a much higher output alternator in mind.

 

[Soylent]

140 amp sticks in my mind but may be wrong. Nothing on the case but a bar code and “12v”. I emailed the installer.

 

[DirtDonk]

Then your plan to add a fuse in the 175 amp range is a good one.
You’ve already got the big charge cable capable of handling that and more, so after adding the fuse, you should be good.
Protection-wise that is…

 

[Soylent]

He returned my email and said 1 wire 90 amp. I thought it was higher. It was purched in 2018 so neither of us can remember lol. I think I’ll get a 100 amp fuse for now and just get the alternator tested when the truck is on the road.

 

[DirtDonk]

Sounds good. With that size cable, you can safely go to, for example, 125 amp fuse.
Safer to have a little more headroom in case the alternator puts out more than rated amperage.
Besides, it’s protecting the cable, and that cable can handle a lot more than 125 A!

 

[Soylent]

Ok. I’ll order the 125a

 

[DirtDonk]

Since your ammeter no longer functions as originally designed, plan to get yourself a nice voltmeter.
Whether an in-dash unit that replaces the old ammeter, or a standalone unit, it’ll give you some peace of mind knowing what is going on with the electrical system.
I happen to like the kind that just sticks into the cigar lighter with a clean digital readout.
But whatever you like and can easily read is the best.

 

[Soylent]

Never heard of one like that. I’ll have to check that out.

 

[DirtDonk]

They're actually pretty cool and can even be swapped from vehicle to vehicle as needed.
As a quick test they're great, but if you don't need the lighter for other reasons, they can stay in place and be your constant monitor if desired.
And at least for these early stages, or until you find a more suitable permanent solution, it's a winner.

Paul

 

[Soylent]

They're actually pretty cool and can even be swapped from vehicle to vehicle as needed.
As a quick test they're great, but if you don't need the lighter for other reasons, they can stay in place and be your constant monitor if desired.
And at least for these early stages, or until you find a more suitable permanent solution, it's a winner.

Paul

I was going to send my gauge to @fallingdown for an update but this solution will let me put that off a bit or until I send it off