Need help with alternator compatability

[jeepjseries]

My 77 has the externally regulated alternator. To test the alternator run a jumper wire from the fld and batt post on the back of the alternator if it charges bad wiring or regulator, if not bad alternator.

[Tigger4X]

yer spittin Greek ...

paint by numbers is my friend. I have no clue what an FLD and BATT POST are much less where they are located other than on the alternator.


IF its the alternator I need to check the wiring on the back of it and make sure the '70 and '74 are compatible because the regulators are NOT

[jeepjseries]

The back of the alternator should be the only two post with wires connected to them. Also they are marked dunno how old or dirty it is, but it's there. One supplies 12 volts other is how the regulator controls the output of the alternator.

[Tigger4X]

This is the same pic as posted much further above and is the actual alternator in my '70 J-3000 and I see more than just two "posts" and I dont see any marks ~~~>




And are you talking about the '70 alternator or the '74 alternator? The regulators are different so

[jeepjseries]

Can't quite see the picture well, but it looks as if there is no marks. What all did you have to disconnect to remove it. I am pretty sure two of those are what causes it to charge. Assuming that maybe some of the others are grounds. On the 77 there are multiple posts but most are unused grounds.

[Tigger4X]

The two sets of wiring that attach to the '70 alternator pictured above ...




The green wire in the middle of the bottom picture attaches to the "blade" post at about 9 o'clock ... IIRC the red wire in the upper pic is on the middle post at 6 o'clock and the red wire in the bottom pic is on one of the posts next to it ... the black wire in the upper pic and the white wire in the bottom pic are on the post at the 2 o'clock position.



I'll have to take a pic of the back of the '74 alternator tomorrow when its light out supposing we arent getting hammered with rain.

[serehill]

Got to do it`

You know there are a few po mods mixed into this this also making this difficult to detail. You may be best off to completly rewire especially if you're going to delco alternator 3 wire. I think rather than try to figure out what you can do to rig this back together maybe just start from scratch. Tgreese is headed in the right direction. It just seems your going through a lot of stuff for an elusive goal I have not figured that out yet to be honest. Excellent reason for a single wire. IN MY OPINION ONLY. All this stuff you're working with has seen better days. Risk are high you may damage more.
Taking the diagram used earlier & simply tracing the wires you have & eliminanting everything else would be best since PO motives were not known.
LOL if nothing just me posting about an alternator will get more results.

[Tigger4X]

Thanks for the input SEREHILL. I'm just trying to limp by on what I have for a short bit which is why I was hoping the alternator on my '74 J-10 would be compatible with the one on my '70 J-3000.

I went to O'Really and found out for sure that the alternator is definitely muerto as suspected. A friend told me about aplace here in town that does rebuilds so I'm going to check that out on monday.

In taking a closer look a just bit ago I finally noticed that the 4th wire (yellow) on the '74 regulator goes to the starter solenoid and the other three go to the alternator just like they do on the '70. The mounts on both alternators look identical and they both put out 37 amps. Hopefully both of these tidbits of info will lead to being able to swap out the alternator for now.



A couple of questions for you all ...

1) I know this is gonna sound really shtoopid, but does the '70 J-3000 have an ammeter type circuit It doesnt have the ammeter gauge, just an idiot light.

2) If I was to up the amps my current alternator puts out in the '70 J-3000 will there be any backlash or risk of car B que?



Thanks again everybody

[serehill]

well

The light is basically doing the same thing physically as the meter as far as the alternator is concerned.

You shouldn't have to do the bypass on the light. It isn't as likely to Car b que!! (I like that) The ampmeter circuit is the one that is in jeoperody of that. Not going to belabor why but that's the case. You're Good

I would just repair also rather than do all the swap thing. You are correct both external units function in the same way & the wiring routes & colors may be different. Not to mention what a PO may have done. Anyway it sounds like you have your path resolved that's cool.

[Tigger4X]

FINALLY GOT THE '74 ALT PULLED ...

I finally got the '74s alternator pulled and noticed that the wiring is different than the '70. The first two pics are the '74 and the next two are the '70. I dont care if I have to modify the wire ends to get by on this one for now. I have to get this bugger running to go pick up the "new" bed for The Ugly before I lose it.









Please remember I'm a total simpleton when it comes to electrical and wiring diagrams. I just need to know where each wire goes like Tab A into Slot B kinda paint by numbers stuff.

[autoarcheologist]

Don't know if this will help or not, but I upgraded an externally regulated alternator on my Alfa to a later, internally regulated version.

My externally regulated alt looked like your top picture, the '74 version.

My internally looked more like the lower, '70 version. What was the difference? No wires on the later version going to the external regulator.

If you flip the '70 alternator photo over 180 degrees, it looks the same as the '74, but without the plug on the right side, which I bet goes to the external regulator.

The '70 regulator looks to be newer or rebuilt and maybe has an internal regulator? In which case, you only need two wires (I think), one is the 12V output, the other goes to the dummy light.

Have you looked through this?

http://oljeep.com/gw/alt/edge_Alternator_Theory.html#Section_5

Unfortunately I don't know enough about FSJ's yet to know what the mess of wires in the second diagram is supposed to connect to.

Good luck, doesn't sound like fun.

[Tigger4X]

Both of these alternators are externally regulated. I'd love to splice in the wiring from the '87 Grand Wag I have and stick the '87s internally regulated alternator in my '70 and call it done. I know it CAN be done I just dont know which wires correspond to which. Once I have that squared away I can do all of the soldering and such to finish it up.

Thanks for the link. BTDT and cant make heads or tails of it to save my life hence the "Tab A into Slot B" and "paint by numbers" comments.