How do I use a 4G alternator in a '93 Ranger (stock 3G)?

[Carguy3J]

Well, the title pretty much says it all. I have a '93 Ranger.
It came stock with a 95amp small case 3G. I am currently running a large case 3G I pulled out of my scrap pile. I had though it was a 130A, but testing it showed it to only put out a max of 110A.

Now, I just acquired a fresh and shiny Duralast 4G 130A, which is listed for a 2003 Explorer SOHC 4.0L (among other applications). I got it for free, so I would like to try to use it. Obviously, it will physically bolt-in. My concern is the wiring.

My 3G alt has the 3-wire d-plug with all 3 terminals having wires on the harness side. It also has the 1-wire small square connector, for the charge indicator light.

The new 4G alt does NOT have the 1-wire square plug. Also, the remains of the donor vehicle harness that was attached only has 2 of the 3 "terminals" on the d-plug "filled", with the middle slot empty. The 4G alt itself DOES still have 3 blades in the d-plug receptacle.

So, what, if any, wiring mods do I need to make, in order to plug in this 4G alt.? I would prefer to do it in a way that will still allow me to quickly plug a 3G back in, in the future.

Also, the electrical "guru" at the parts store seemed to think I have some other electrical problem somewhere. The reason being, if I unplug the 1-wire charge indicator plug, from the alt, the light comes on, on the dash. He thinks this should not happen, and indicates a short somewhere. That doesn't make sense to me. If I unplug the wire that is used to indicate a "no charge" condition, then why shouldn't the light come on? Is he right, that I have a problem elsewhere?

 

[Nixthebomb]

I ran an alternator from a SOHC in my OHV for close to two years without that plug installed before I upgraded to a High Output, never had any issues. My alternator guy was surprised when he saw it, but stated that it's just redundancy on the 3G.

 

[Maniak]

The single wire and the middle wire in the 3 wire plus are for the Stator wire.

When I've done 3g upgrades (replaced 1g and 2g) I just connected the middle wire to the single wire..

It sounds like that is done internally on the 4g.

From the wiring pics I've seen on the 'net the 3g and 4g are wired the same.. (electrically, not physically)..

So, If I was attempting this I would just put the 4g where the 3g was, not worry about the single plug and if I was really worried about the S wire on the 3g harness (3 plug connector) I would just snip the middle wire OR cut/replace the the 3 plug with the one from the 4g..

Couple pics I found on the 'net.
3g:

4g:

~Mark

 

[Carguy3J]

Thanks guys. Unfortunately, I discovered another problem yesterday. Surprisingly, the 4G doesn't fit. It is a t mount, just like the old one, but the bolt pattern is smaller then what is on my '93 Ranger 4.0L OHV.
The new 4G I have is listed for a 2003 Explorer 4.0L sohc. Does this make sense, that it won't fit, or did the rebuilders put the wrong unit in the box?

I guess I may have a nice shiny "New" 4G for sale shortly......

 

[CDW6212R]

I'm not an expert either, but it sounds like you have the common 4G unit that will work on the 302 and the SOHC 4.0's. The OHV 4.0 uses the odd alternator, the bolt pattern is off a bit. I bought my 99 SOHC truck without an alternator, and the salvage yard grabbed one and bolted it on. I found out that it was the OHV unit, and though the truck would run, the dash light was on. I swapped it out before driving the truck, and used the other OHV unit on my 91 Explorer when it lost one.

You would probably do best to sell that one, and buy a 4G unit that fits your truck, assuming that there is one which bolts on. You can correct the wiring for any alternator for any vehicle, the housing and having it bolt on is the first step though.

 

[Nixthebomb]

Yeah the one I pulled from a SOHC only bolted on the front two bolts and not the back one, never worried about it. Just tightened down the other two real good, never had any issues