Alternator Wiring Assistance

‘72 304

My replacement alternator is slightly different than than what was on the Jeep when I got it and want to make sure I’m connecting things right. Also, my wiring set up, which appears to be slightly different from the factory, is different than the TSM. I carefully unwrapped and checked all the wires in the engine bay. I have a red primary wire to the alternator, which goes through the loom all the way to the dash, not sure what to originally because it was cut behind the dash, and then some how comes back as a primary yellow wire to the starter solenoid.

So, to connect this alternator, in addition to the two-blade plug that is obvious, I need to connect the other two remaining connections to posts. I believe the large primary red wire that I put a new ring connect on will connect to the larger post with the red felt under it (#1)? The two merged gray wires will connect to the post with the yellow felt under it (#2)? Assuming I have this right, do I need to do anything with post #3? I see a ground in the TSM but thought that might mean it grounds via mounting to the alternator bracket.

 

Where's the original?

Do you have an ammeter?

 

Here’s the original.
Yes, it had an ammeter originally but I want to go with a voltmeter instead.

 

Looks the same to me.



This is from the '72 TSM. The TSM also has helpful diagrams of both the circuit (in section 3) and of the harness routing in section 22. Did you overlook this part? Not sure what else is needed.

Only the Renegade in 1972 got an ammeter. If there is an ammeter on the dash, it's been added or your Jeep is a Renegade? All the charging current goes through the ammeter, so the extra wires are for that.

 

Hmmm, never thought about it being a renegade originally. That’s interesting and pretty cool if it was.

Thanks. I saw that pic in section 3. I guess what is throwing me off are the colors under the posts. One is yellow on the new one while both were red on the old one. In section 22, the diagram says wire #11 is a yellow wire, but mine is red. I guess I was just over thinking it. I’ll attach the combined gray wires to the yellow post and just leave the other post (#3) with nothing attached?

 

Have you read the circuit diagram, Sec 3 fig 10? Anything that's given the ground symbol is connected together. I would check if #3 is connected to the case, even though it has an insulated washer under it. It may be connected to nothing.

Aside from ground, there are only 3 wires to the alternator. Grey takes power from the alternator to run the regulator, green with trace is the regulated current to the rotor, and yellow is the alternator output. The regulator also needs the "bootstrap" voltage from the switch to start the alternator charging. Not much more to it.

 

I would also comment - the ammeter circuit also provides power to the dash and lights. There will be a splice under the dash that branches to power these. You can connect the alternator output directly to the starter solenoid (the yellow wire), but you need to keep that power feed that goes to the dash somehow. Likely that wire is red, given what you've told me.

 

Another comment about the alternator - let me describe how these rebuilt components are handled.

The cores come in from wrecking yards and exchange. You may have seen the big piles of starters, alternators, etc. at the pick and pull. When they arrive, they are broken down into their component parts. If the part is going to be replaced (diodes etc.) these are discarded. The resulting parts are cleaned and put into bins with like parts. All connection to the original assembly is lost.

Back when I was working parts counter, the chain had its own captive rebuilding plant. They advertised remans as a central part of their business. When you turn in a core, it goes into a pile at the store. That's the end of any possible recovery of that part. Once the part leaves the store, it ends up in a dumpster-sized bin with all the other cores - there's no accounting for where it came from or what car it fits.

There are workers (in Mexico or?) that have a spec for each stocking number that the company sells. Someone in the company has used the original manufacture's literature and (I presume) the Hollander guide to make a set of offerings that cover the maximum number of applications with the minimum number of stocking numbers. When the warehouse needs stock, they call to the assembly plant and some worker puts together that number from a recipe. The remans are then boxed and sent to the warehouse for distribution and sale.

I expect any application they can't make money on (too little demand or requires too much investment in warehousing?) or can't maintain stock is eliminated. Some houses (Cardone) will rebuild your core, likely for one or both of these reasons.

Anyway, about your post #3 with the insulated washer under it. On the original alternator, it looks like it's connected to the case. At the rebuilding plant, the case half was stripped of all the loose parts and these posts were replaced with new. The worker likely fills the hole with the part she/he has, which includes the insulating washer. I would not be surprised if both those unused posts are now insulated from the case and going nowhere. The noise suppressor still works because its body grounds directly to the case, rather than grounding to the post via the clamp.

You can take the alternators apart and look at the changes in construction, if any. Note that the brush plate screws are now one size larger - that's just expedient. The old screws went in the trash.

Not essential info, but I thought it might be interesting.