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I was bouncing back and forth with the idea of upgrading to a 3G alternator on my 91 E-350 to meet my increasing electrical demands, and took a look at mine. I noticed that it looks like someone had replaced the plug with a single wire connection and this unfortunately has me stumped. Does anyone know what is going on here? Or how I would go about doing the 3g upgrade since I'm missing what I assume is a needed wire? If more photos are needed, just let me know what to take a photo of.
My guess is that the "unused terminal" is supposed to go to the cluster panel light that alerts you when the Alternator is NOT charging.
IF,
you choose a MechMan alternator, they only use 2 wires,
you can just follow the wire loom back to see what they did with the "other wire".
the "I" wire is for the key switch or "Ignition"
the other wire is Feedback from the Alternator that signals the Cluster Panel if the alternator is charging, or not.
I have the 320A version, the Blue & yellow wires are for the Alternator, don't know what the others go to, without tracing them out.
I should have mentioned, that you can provide the "missing wire" as I had to do.
the "I" wire for my truck is broken somewhere between the Key Switch and the Alternator. chased it for months, 2 weeks ago I decided it is simply not worth the effort to find it.
So, I got an "Add a Fuse" adapter, pulled the Fuse in the Fuse Panel marked F2.45 which is a 10 amp mini fuse, the adapter uses the same size fuse, so put a 10 amp there also.
Now when I turn the key on, the alternator works like it should.
You can do the same for a newer, high output alternator.
I should have mentioned, that you can provide the "missing wire" as I had to do.
the "I" wire for my truck is broken somewhere between the Key Switch and the Alternator. chased it for months, 2 weeks ago I decided it is simply not worth the effort to find it.
So, I got an "Add a Fuse" adapter, pulled the Fuse in the Fuse Panel marked F2.45 which is a 10 amp mini fuse, the adapter uses the same size fuse, so put a 10 amp there also.
Now when I turn the key on, the alternator works like it should.
You can do the same for a newer, high output alternator.
Thank you, thats actually helpful for a few different things.
I bought a one wire 3G some time ago, BTW its an easy swap on the inline 6, but the V8 requires cutting the bracket from what I understand, it has a higher idle amperage than other choices, but after a talk with my alternator shop, the internals for 200 amp or higher is completely unavailable, I tried everywhere, the one guy listing it, I called him personally before ordering, he assured me he could get it, a week later I was given a refund, he found he could not, looking at what is possible to put in the air pump location on my 89 E150, run the engine on the stock unit, and all accessories directed to a secondary alternator.
